I'm sort of stuck at a party where parents host 75 children (or 100 children, as the PP feels they should) to a theme park. I've seen TV shows with this stuff, but... wow. It still blows my mind.
While our parties were on a whole other level (lower, much lower) I never invited the entire class to my kid's parties. I think the biggest party had 8-10 kids, in the backyard.
I don't know anyone who hosted an event (even a backyard hot dog event) and invited the entire class. I'd guess, at most, my daughter was invited to two parties a year.
I can't imagine attending 75-100 parties like the PP is describing in a year (which is what would happen if everyone is invited to every event). When do you have time for everything else? There are only 52 weeks in a year? Do people really want/expect their child to be invited to that many events?! I'd be exhausted just providing the transportation.