While "acrylic" can be defined as a wide range of materials "plastic, plexy, poly, or marketing terms like hesalite", plenty of modern high end sport watches still come with these crystals. Usually ones that are still intended as some sort of sport or tool use, or just because the model always did. Some may have two versions, one with the above for one crowd and one with sapphire as they know many people will not use it for the intended task. It is also still common for micro-brand sport and tool watches, I suspect their volume is too low to justify tooling for sapphire.
Having just polished up the acrylic on the old Hamilton I recently bought, I'm much less worried about owning watches with these crystals. Sure, they scratch easy, but they also fix easy, and look great after the fact.
Mineral glass (or worse yet just glass) is usually the sign of cheap low to mid grade.... with acrylic also still used here as well. If you break a cheap glass crystal acrylic also makes for an easy replacement...
Worse than acrylic, for sure. Scratches almost as easily, but much harder to fix.
Have you tried and compared them, side by side?
I ended up using Polywatch on the above Hamilton, especially after watching a few YouTube videos favourably comparing it to some alternatives, like toothpaste. Sure, it's a lot for a little, but I know it's designed for purpose, and all I need is a little anyway. Sure, I could have bought lots more of some similar product for much less per ml, but then what? At least the tiny Polywatch tube doesn't take up much space in the drawer with my cheapo Amazon repair tools etc.
It's hard to really capture the improvement with a photo, as the shine and colour of the crystal don't really get captured and the lighting is different, but here's a before and after:
To the naked eye, the after is a massive improvement, clearer, shinier, looks like a new watch. There's still a few spots (just dots, not lines) where the damage was deeper and harder to polish out, but you can't see them unless you shine a bright light on it and catch the shadows. The best bit is the polishing highlights how mint the linen dial is, and lets it catch the light as intended...
I think I should sell this one. 1969. Never opened. Runs. Likely needs service.
View attachment 65455
Dang. That is stunning. It's a good thing for me that I've gone overboard on watches lately, or I'd be making an offer...
Love the Gruen. Does the movement come out through the crystal?
The above Hamilton from the mid-'60s is like that, and looks an awful lot like that Gruen, to the point where one was clearly 'inspired' by the other. Similar to your Benrus, they sold it as being 'dustproof', though I'm not sure quite how much dust would get through even a snap-in case back.