Whether it's true or false, the statement was:
<<<<many would not see any of Europe if they didn’t cruise.>>>>

Not 'many could not see...'
So your argument that people are capable of booking a land visit is irrelevant. And even cruisers are a modest percentage of all European visitors, the statement said 'many' not 'most'.
I don't wish to be overly critical but it helps to frame the argument properly.

The statement may have some level of credence. For example, we know that some travelers are very loyal to cruising, taking cruises over and over again. They may also grow loyal to a specific cruise line and every cruise taken, no matter the destination, has been great for them. So they may know 100% that they want to take a cruise but where to? "Oh I see that Norwegian does European cruises too. let's try that next year". Some of those types of travelers might never get the inspiration to travel to Europe - they are going there simply as a new and different cruise destination. They may also have cruise loyalty points that enable a more expensive trip than they would normally take. "Hey we've got all these points, let's splash out this time...how bout Europe?"

Like Alaska. Many people might decide to visit Alaska and then decide HOW to visit - cruise, land tour, independent, etc. But I bet loads of loyal cruise fans go there simply as a new cruise destination. And their cruise friends are all talking about it. For those people, it might be unlikely that they'd just choose to visit Alaska for the sake of visiting Alaska. They go there because they love cruises and it's a hot cruise destination.

It's not much different from many things that people would not naturally try or buy but if one of their favourite brands starts selling it, they are more likely to try it. You may not naturally choose to see an action film but if one of your favourite actresses is starring in it, you'll go see it. Or if you never really sought out hummus but one of your favourite restaurants puts it on the menu, you might be inclined to try it where otherwise you might not.

If you are so keen on being argumentative... Define "many".

Argumentative? Well you're the one who put out there that someone's statement was "bizarre and open to serious question" (your very bold words) and only offered weak, irrelevant and illogical arguments in support of that very bold position. If you stand by your bold position, give us a proper argument or retract it We've given enough. Your turn or retract with apologies.

You were the one who made the initial claim. I am not retracting anything, but I am done going back and forth with someone who has no data to back up their assertions. Bye.

I have a love hate relationship with cruises.

I love that you see a lot of places, not having to repack when going place to place, doing some activities that I don't normally get to do and having something to do the whole entire time. You also don't have to worry about directions in finding something.

I hate not having more than a few hours in one place, having to choose what 1 thing to do or see in a place, no shopping, eating what seems like the same food over and over and having to dress up for dinner as I am a casual person. Not to mention if you pick the early dinner, it doesn't give that much time to freshen up for dinner.

I think for me, I prefer to not cruise but wouldn't rule it out completely. I did an overnight ferry from Stockholm to Helsinki and back. I very much enjoyed it and would have loved another night to another place. It wasn't like a standard cruise at all.

I got ya. I will have to check that out thursday. Not all boats will be like a traditional cruise and I see the benefits traveling over land than by boat. I like a happy medium as I do love to shop and sightsee but find I can't do both on a cruise followed by the boring food. Funny when I'm not even a foodie.

Oh, the irony of that statement!

No, HappyTrvlr made the initial claim/assertion, not me.

We have travelled many times in Italy and Germany. If you plan in advance, you will have no problems. We did all our travelling by train which is not difficult at all. After your first time, you'll already be a pro. However, in many countries it's best to buy the tickets ahead of time online. I also recommend Man in Seat 61. You can also write to Mark (the man in seat 61 himself) and he can advise you on anything specific. People are very helpful and we've even had people walk with us part of the way to make sure we're in the right direction (in Italy).
A cruise is great if you want to enjoy the cruising experience on board. However,the amount of time you spend in each port is quite short. We did a cruise to the Baltic Sea because we knew that we wouldn't do a regular trip to any of the places but it was frustrating sometimes because we wanted to spend more time! So if what's on land interests more than the food and entertainment on the ship(I'm not knocking it - if that's what you want, it's great.), go for a regular trip.
I am an English speaker too and I never had any problems even if nobody spoke English. That's not the case in well toured areas in Germany and Italy.
I'd say go for it.

I meant "That's the case in well toured....."

In that case, why do so many inhabitants of those islands say they're "going to Europe" for their holidays, or that they've "never been to Europe"?

You know that food from many regions in India is not that spicy at all, right? Indian restaurateurs suppose their European customers want it "spicy" (the vindaloo challenge) and so they oblige.

Yes, I am aware of that. I happen to like my food spicy, which is why I eat in Indian and Thai restaurants. Unfortunately, in the US the assumption is that US customers can't tolerate spice even when they ask for it. I believe this to be based on observation...