TBC is still an old school MMORPG concept. I don’t think it’s condescending in any form when people say, “maybe the game isn’t for you”. Being efficient at trash can be learned just like boss fights. In fact, we make an extra effort to increase our efficiency on trash just as much as the boss fights. Does the trash suck? Yes. Is it probably the biggest contributing factor for 8/10 guilds? Yes. But suck it up and learn it. Stop talking about League or Netflix or whatever else in between pulls - wasting 5 minutes. Every minute counts.
That being said, people are making the assumption that everyone or even most people are quitting because of being stuck at 8/10. I don’t think that is the primary reason from my experience.
Edit: fwiw, We are still 8/10 and we used to raid 5 hours a week. We had ample to for progression, but felt like we needed that extra hour. Point being, even with 5 hours a week, we were able to get some good attempts in. That being said, our core 20 players or so are very, very good. We just needed to solidify the rest of the spots - even if they are lesser players. Consistency is king.