I do a lot of events on FFXIV, primarily the crystal data center but i've been asked to do events on aether/primal before.

I run mostly roleplay events, but i've done charities, stream events and artparties etc.
I've accidentally shut down wards, and have closed many houses due to congestion.
I'm no stranger to closed off worlds from before SB, as i've been around doing this for more than 10ish years or so. It's my hobby, and I enjoy making community events for the RPers and others.

There has always been an issue with congestion, A normal zone has a limit of 300ish players but I believe since DT we've seen those numbers go up (Snake fate waiting)
A large house can hold about 120 players, A medium can hold up to 83 or so and a small can hold around 50 or so in the house before you can no longer have people come inside and people get stuck in fc rooms lol.

We've also found in our many years that if too many people crowd an Aetheryte or stand outside a house, you can't travel out of your house or use that aetheryte as the game thinks the instance is at max capacity. (Work around was to teleport outside of the area and come join the group hoofin it style)

That being said, i'm used to dealing with a certain amount of frustration and as an event runner hearing people be upset at not being able to make it to events. I've heard it from 'But i'm not on balmung/mateus etc so i can't make it '
'But i'm not on Crystal dc so I can't make it '

In most issues of past congestions woes there was work arounds. The DC travel currently frankly reminds me old housing from shb where you clicked your heart out and that frankly is incredibly frustrating to me. There doesn't seem to be as much work around for the DC Travel restrictions, itself.

For venue rp, the last few I've done since the changes were 'light' but expected for a new savage drop and new expac, so I wasn't aware of the other venue owners suffering even less turn outs than I did. And generally when I see something going on to this magnitude I ask/reach out and see what is causing a decline and everyone agreed it was DC Travel bans.

So it really does seem that us trying to group together for activity are really finding it frustrating, as right now the only work around seems to be 'if you can data hop earlier to get around prime times and hang out until event time you have a better chance.' Which feeds into the issue of congestion for everyone.

There doesn't seem to be any workaround outside of somehow convincing the playerbase themselves to stop afking in clumps on servers not their homeworld. Which frankly isn't going to happen, they are not getting out of their chairs.

A pretty wordy tl;dr of
I've experienced this annoyance, and i'm experiencing it again in the weirdest of ways and SE please can you give us more server space as thats the only thing I can think of to fix the issues.