As far as time goes, not everyone can dedicate days of time when content is released to rush through it immediately. I took months to make vision and didn't have time to even start the season of the dragon stuff until the week of Return to Sandswept Isle. I was fortunate to have some free time to catch up.
Addressed above.
It's not an ok thing for some people to get something done immediately and others to take days or longer. "It's RNG" is never an appropriate response. I shouldn't have to explain this. Even legendary precursors have a way to craft since they just don't drop for some people.
None of this matters if there is no one on the map. There is no group to find in lfg if no one is there. Again, "I did it." just doesn't matter here. As time goes on, things need to be updated. It really wouldn't be hard to update old map venders with new rewards to incentivize going there beyond a very limited special event. When people are finished with the return to achievements, do they have a reason to go back? Not really. Heck, people still go to Bjora Marches all the time because the map currency is useful elsewhere. That's enough proof of concept right there to prove my point.