That doesn’t accurately reflect the reality of gas bocks on a modern AR. Adjustable gas blocks are used more than ever these days as more people understand the advantages of a properly tuned rifle, and as suppressors become more common. They are definitely not a hold over from earlier days as you imply.
The reason they’re being used is a direct result of most barrels being over gassed from the factory, which itself is a result of the wide variety of ammo in use and manufacturers wanting to avoid paying for barrel returns. That part makes sense for the manufacturers; you get a lot more happy customers if your barrels are a bit over gassed than if they only run on good ammo. You kind of have to understand probability distributions to really get into this, but the point is that most barrels are set up to work with the largest variation of ammo and rifles possible. That means some people end up with setups that are just right, and a few are even under gassed still, but most of us end up with overgassed barrels. (Of course there are exceptions, we can all agree on that)
Adding a suppressor to an over gassed barrel makes it even more over gassed. Guys are talking here about not wanting a system that’s barely on the edge of functioning, but how many realize how close their rifle is to that line on the other end (too far over gassed) with a suppressor on it? I don’t remember how many times I’ve looked at brass from rifles used this way and seen major signs of early unlocking, including rims being ripped partly off. A setup like that is just a question of when, not if, it will fail.
And yeah, there’s a lot of improvement in newer suppressors designed for semi auto rifles, and that’s a great thing. But even the best of them still makes a big difference between suppressed and unsuppressed and can benefit from proper gas tuning.
None of the comments or concerns about click adjustments, springs, or leaves have anything to do with the OP’s question though. That’s not the kind of gas block he has, if I understand what he’s got. That Seekins block has just a simple set screw partially blocking the hole; there’s not much to go wrong if it’s set up correctly from the start. That type of gas block isn’t for everyone, but if they fail it’s pretty much always user error. Just set it and leave it alone; no fiddling, no maintenance.