PCs typically come with dialup modems, all you do is plug in the phone cable and get a CD from an internet provider which sets it up. True, broadband isn't hard but telling a scared PC owner about USB modems, routers and microfilters SOUNDS quite tricky!
True, maybe shmup-fans aren't casual gamers in the true sense - but many of them might be older guys, to whom shmups are the games they played as a child. For them shmups could be casual games.
PC typically come with a dialup modems?
Portable pc maybe, but PC typically have an ethernet connexion and no dialup modem (maybe in US).
Most provider in france have only one box, with a phone connexion, and an ethernet connexion. You plug and it work ( without any connexion parameter, login or driver). It's a lot more simple than any modem installation!