You can't deny that
- It's spammier and slower (that's a fact, 9 people instead of 6 makes the game longer)
- The unlock list contains some terrible weapons (unless you think they're all balanced - which they're not)
- The average HL player IS less skilled than the average 6v6 player, due to what Pan said
- Metagame is simpler
Worse maps/gamemodes was an opinion, you're right.