"<i>smaller hotels might not have 4 rooms available for your dates. . . .</i>"

And even if they do all the rooms may not be the same size/quality/whatever. Plus you can bet all the bedrooms in a villa or apartment won't be equal, all ensuite. Are people going to pay less if they have a lesser room?

BTW, in spite of the financial complications I mentioned, you can have a fun time with a group. It's just that you all need to go into this having established the same expectations and commitment before you go.

Another benefit of slowing down the itinerary is that it allows people to break off into smaller groups for sightseeing/shopping/museums/etc. more easily. When you are on the move, it makes this harder.

Oh, and in Amsterdam, if the weather is nice, I prefer to get a joint to go and go to the park to smoke (take a blanket, lay back and watch the clouds, make sure you bring snacks) Coffeeshops are ok, but they are smokey ;-)