Generic users should at first join a recommended server. Those don't require essays. If they wanna join some niche server that has "high standards" in one way or another, then they shouldn't expect the same requirements.

If you wanna promote lemmy, suggest ppl join any of the recommended servers that don't require essays. I see no incompatibility with mass adoption (what you propose) and some servers not allowing everyone to join. Just promote the ones that do allow everyone to join and don't promote any list of servers that puts the essay-requiring ones at the top cuz, as you say, that will obviously make it so very few people join.