Well I think there are enough games which attract both types of players and there is a lot of friction. Most Blizzard games fall into that category.
World of Warcraft and Overwatch attracted a lot of casual gamers and it is a shame some competitive players give them a hard time.
Taking World of Warcraft as an example, it would actually make more sense for competitive players to play with their guilds only. But many want to use the random dungeon tool additionally, out of lazyness in most cases, and than go ballistic on casuals.
If you can’t deal with players being in a dungeon the first time or doing LFR, than don’t use the tool…