ART!
Deluxe Unhuman
The biggest game I've been in had 8 players. In DnD3.5, it was a nightmare. The biggest I've run has been maybe 5 players.
I'd love to learn how to run a game with over 6 players in a fun way. In some systems, I think it might be impossible.
I've run 5E for 9 players. It was a strain on my multi-tasking capacity, and combats took longer, but it worked and everybody had fun.
I tend to be a "more the merrier" kind of person, and when it comes to face-to-face gaming groups my rule is "never turn away a good player", because I've seen too many gaming groups fall apart from the inability to get enough people at the table each week.
In my experience, if the players are friendly with each other, the more players I have means less work for me when it comes to generating fun; they do that themselves. With more people my job as GM becomes more about making sure things keep happening.
So, it's not impossible, but it might not be to your tastes, which is totally valid.