Maybe they were simply trained in the French Tourism industry?
I still remember the time we followed a guide book route walking up the river to Chenonceau where you are to enter from the back way. But the guard there (letting people back in who had come through to the gardens and wanted to reenter) refused to allow us in that way. There was no way to get to the other side and the main entrance except to go north nearly a mile and cross a regular bridge then come back down river. I kept saying, "just hold my passport while I go get the ticket" and "one of us will wait here while the other one gets the tickets", but the rule was that we couldn't get in that way (despite the guidebook recommending that route). Sometimes people in authority like to show their power regardless of how silly it all is.

Unfortunately if you get your application wrong, this is what you get. The Russian visa application process gets the most publicity on how difficult it can be, but other countries behave in the same way. French visas generally speaking, can be difficult to obtain for Russian citizens.

Lining up outside the consulate is quite normal, at the London consulate the lines started at about 4-5am, if you did not make it through the gate by 1200 you were turned away. Using an agency can bypass these lines, since they have a pass to let them in. Also an agency can employ a Russian national to handle the applications which is helpful in smoothing things over when necessary and even getting the consulate to accept an application with small mistakes. Nowadays in the UK, you can only apply via an agency, which means they filter out the errors before they reach the consulate.

It is also true that different consulates can behave differently and sometimes even set their own rules, or change the rules from one day to the next, as you have experienced. There are rules however, about applying for visas outside your own country, unless you have residency status, so best check.