Because content has changed since 2.0. It's not the same difficulty. Savage has changed from 2.0, and we have ultimate fights added in SB. With higher difficulty, carrying your own weight is essential to the group's success. Even if you clear said content, those that are under performing need to be addressed.
Those hiding their logs the majority of the times are doing so because it's bad. There are exceptions, but those are rare. If we assumed there was no FFlogs, then what would prevent a player that barely cleared a savage fight and isn't good about its mechanics from joining a farm group that want to clear the fight fast to prog the next fight? They wouldn't know, until they pull multiple times and realize that they're bad at this fight. And in the case of door bosses, if they passed that boss, then that's more time wasted. And if the other kicked that player or called him bad, they'd come here to the forums and say "WoW refugees are toxic and elitist!"
Let me give you an example of an actual log I saw. A party farming Suzaku EX managed to kill it 3 times with two DPS performing even lower than the tanks in some of the fights. They barely killed it before enrage at one fight because the SAM and the BLM had were pulling 7k+ DPS those fights (the SAM had a gold parse and the BLM a purple parse in some of them). So according to your logic, this OK because they killed it. And if they were to tell the other two DPS to carry their own weight, they will be toxic, right?
Anything outside of high end duties is fine if they were to follow your baseline. But in high end duties, then be prepared to be criticized and asked to actually put in the effort.
I'm a mouse clicker and I manage to clear content normally lol.
Let me ask you this.. Is it OK if I queue to Ala Mhigo with ilvl 270? We're still gonna clear the dungeon, there's no doubt about that. But do you consider it OK to do so?