As a casual whose main is now at the top end of T2:
I found there's enough stuff you get through daily logins, special events like the current chicken island, and apologies for maintenance to keep your main, at least, in the shards you need for upgrading. It probably helped that I kept getting chests full of things and didn't just open them right away because I wasn't sure what I needed, so by the time I hit T1 and then T2 I had plenty of the main ingredient you need for honing your equipment to higher levels just waiting for me.
Only one of those types of shards are character-bound, the others you'll get a lot of unbound amounts you can put in your roster bank for your alts to go at. I don't know if there's a way to transfer harmony shards and the other T1 mats, though, so my main might just have a lot of now-useless stuff from the lower levels I can't do anything with.
It's fortunate that you can solo pretty much all content until you get to North Vern - level 50 isn't enough, you have to also have progressed the main quest to a certain point to start on the tiers. But between the ability to level up your alts either with powerpasses or gold, and a clear drop off in new players, you're going to be doing pretty much all the earlier content including dungeons solo. There's allegedly helpful guilds out there, but I've pretty much only dealt with guilds with end game people with no community, brought together because there's a quest to join a guild so people just pick one at random.
You won't look alone if you start, though you'll likely not run into actual players often. The bot issue is insane. I feel like every week during maintenance they get rid of a whole bunch of them, but it only takes a day before they get back up to untenable, queue-to-log-in levels. On my server, you'll basically see hundreds of bezerkers and sorcerers running around with keymash names. If you see either of the classes and they don't have a title or guild, 99% it's a bot. 100% if they never mount up, though I think one of the bot programmes has put in using horses. And they're slowly getting into more and more content as the programme they're running gets updated for more and more areas.
When I started, I could team up for the hard mode of dungeons very quickly. Now, it's just not worth waiting - which isn't a huge loss as you can solo pretty much all of them, even on hard, anyway. You'll miss out on little bits of content because of it - a secret boss room here and there that requires more than one person to access - and that's irritating. World bosses are the same - you used to be able to get a few players together to take one down, but now if you want to beat them at a level-appropriate point you basically have to ask in area chat and hope a high level is passing through and will kill it for you. Though again, once you hit the tier levels, you could go back and kill every ordinary world boss solo.
Basically, I've been taking my time, doing side quests and not focusing on the main story, so most players still playing are the ones that are T3. If you PUG any of the content other people are still doing, especially things like Abyss Raids, you're 95% of the time going to be carried whether you mean it or not. And any PvP that's not the arena where you get equalled isn't worth it until you're at that level.
Amazon is also still changing NPC races - one of the Nerias recently became black on her card, but not the in game model - and a few genders, not remembering to change the text. There's only so much they can wokify it, but they're doing a shoddy job when they do so it's far more obvious than it should be, which makes it worse.
The cinematics are also pretty bad. There's a musical number at one point that's pretty fucking painful, but in general there's also very little effort put into making mouths match - or even move, half the time.
All that said, if you like a Diablo type game with some very fun, different characters to play, there's a lot to get out of it. I even think it's better to level a character yourself rather than solely use the boosts, even though they're either free or cheap enough. I'm certain you get more stuff that way, and you can skip most of the story bits while getting a real feel for the class and figuring out if you like it or not. Playing through story content is very different from what you need for the other content, but it will give you an early insight into any potential problems early. Like, Gunlancers are the only class that has a dash backwards, not forwards, and that becomes surprisingly annoying very quickly.
Tl;dr: the player base has segmented quite solidly already, and the bots will kill the game. But it's free and fun if you like Diablo-type games.