I mean, it's just so weapon, environment and use specific, and also what exactly you're after. There are certainly guns that are fairly "quiet" (ie., 140-150 dB) unsuppressed, subtract 20-30 in earpro from that and that's not bad. If you go look for measurements of magnums and 30cal+ rifles and shotguns and such you'll have no issues finding 165+ levels too. Or if someone is using a short barrel, that's going to be louder then a long one (and compared to a few decades ago even short barreled rifles are now very popular though not something I use). Or are they shooting outdoors or indoors? How much? Someone going out and doing a few dozen rounds of slow deliberate fire a month to stay in practice with some hunting (just a handful of rounds per year) is facing a different combined exposure then someone doing a hundred+ per week. Our knowledge of hearing loss has also changed. People are just plain living longer as well.

Any ear protection is better then nothing and there is certainly more than one way to do it. But damage is cumulative, so it's worth considering what kind of exposure one is seeing. I think lots of people just accept it or don't even know, they "get used to it" which means they've lost high frequency hearing in particular but the ear protection is helping make sure they can still hear conversations and avoid tinnitus ok (or at least raise their odds). The law plus natural human impulse also perverts the situation, people want things they enjoy or think are important to also not have serious drawbacks, industry wants people to feel shooting is safe, and government (not just the law [0]) makes getting a suppressor a real pain in the butt. So there are plenty of incentives for motivated reasoning around the issue further mixing things up. If suppressors were just OTC safety devices I think we'd be looking at a different picture.

Ultimately though I think this is one of a number of medical issues that society overall is slowly waking up to right now (like plastic/"forever chemical" exposure) and will look back on with regret. Noise, not just from firearms but industry, equipment and just environmental exposure, has been under appreciated as a problem despite long standing concerns.

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0: the NFA requires checks, prints/photo, and a $200 tax stamp, so that's in the law and does add some hurdle. But the law does not require the process take an indeterminate 3-12+ months to just do the same look over and over again that happens instantly elsewhere. That's due to poor agency funding and procedures, but is one of the big hurdles.

Although I should note too that there is also State law: in 8 states suppressors are simply flat out illegal even if the federal government approved. So many people simply have no legal option period.

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Edit to your edit: It's worth doing the math for your own situation. Look at long standing NIOSH criteria for sound exposure limits by decibel, ie ( https://www.nonoise.org/hearing/criteria/criteria.htm ). Now go look at gun noise, ie., ( https://www.ammunitiontogo.com/lodge/silencer-guide-with-dec... ). Keep in mind of course that again, this will all vary significantly with gun, ammo, and environment. I'm NOT claiming that no usage of guns without a suppressor can be safe, again there are guns where 20-30 db less will be plenty particularly if used lightly outdoors. But that isn't every gun. Finally go look at anything on NRR (https://www.protectear.com/nrr-rating/) and maximum hearing protection. Keep in mind that factors like fit are crucial.

Then add it all up. If someone is firing a 165 dB gun while others are also firing 150-170 dB guns around them with non-custom fit hearing protection a doing a few hundred rounds once per week, what does that look like vs NIOSH limits? Play with the variables from there. And remember human imperfection. People forget earpro. Someone fires unexpectedly (safely downrange perhaps, hopefully not an ND, but still a surprise). Someone might wear earpro that doesn't fit that well.

So I personally will not shoot unsuppressed. It's just not worth it, the slightest hearing loss is going to cost vastly more money then a suppressor and stamp. It's some extra insurance as well in terms of earpro not doing quite as much as I expected. The long wait truly does suck and I can understand others just not wanting to deal with it, but I think it's an unfortunate state of affairs.

As far as artillery I think there what you might be misremembering is the level of instant hearing loss even with full earpro from even a single shot. If something is 180 dB then you need full head/suit protection or something else, earpro won't even get you below 140 dB at that point which means every shot = a bit more hearing loss.