Why so many

I have noticed a lot of games that contain 6+ players asking for more even 8-10 players asking for more. You would think with these large numbers would slow down a game tremendously not to mention bore  players still waiting on their turn. As far as combat goes that would probably be a nightmare trying to keep up with what everyone is doing.  combat may be resolved quickly meaning some plays did not get a turn and this could happen on numerous times frustrating players that didn't get to do anything. Just my thoughts what about yours

I have 4 players in my current game and I sometimes worry I'm not keeping the pace going fast enough. They assure me that it's no problem but I still sometimes worry about it. I really wouldn't want to have more than 6, even in a face-to-face, tabletop game.

I've found that the number of players really depends on what kind of roleplaying you're doing. If it's more roleplay and less combat than more players may not be a bad thing. On the other hand if it's a hack-and-slash campaign, describing details and encouraging players to describe what they're doing or something, try to keep it from going to a stale "attack, roll, move, next turn". For hack-and-slash I much prefer 4 players at max, but if it's a roleplay focused with less combat, I would go as high as around 8.

A lot of games have 6 listed but request 8 or more due to players flaking out and not showing up for a game. For a lot of games, the average might be around a 50% show of players that said they were interested. At least that is how I understand it. For the others that have over 6 players active, some of them are card games or miniature battle games like battletech still others are also, like Patch mentions, that are mostly roleplaying characterizations and you can have 8 or more easliy doing that.

Well my current campaign has five playrrs with as many as three npcs in it at any one time, and I often have up to nine players running round at the same time as it is a matter of keeping the pace of combat up through anticipation rather than quantity of turns. If every player is fast and doesnt muck ariund then even that many (9) in a combat is easy to manage for your game. If someone dithers about you skip their turn. Even heroes have moments of indecision.

The most likely answer is that the GM just never cleaned out old players from the campaign. Another possible answer is that they use the same campaign to run multiple groups.

The main reason I've seen is that its hard to garuntee who will show up.  I have had about 10 in two campaigns, and regular attendance varied from 2-8.