It was gated since the start of MoP. No point linking Mogushan since ofc it didn't have tier but can confirm that was gated too. Was just less time than it is now because of course they released raids faster. Also I never remember ever our casual guild at the time telling us to go do LFR for our tier. Our raid leader said it would be nice if we did it for our Sha Touched weapons so it would help distribution a bit in normals but that's it. And even then he didn't make us. Only people who are forced to feel that they need to do LFR are people who really care about that little extra.
https://worldofwarcraft.com/en-us/news/7705231