I don't think it is the industry standard as dovetail is widely used as well, on air rifles as well as PB rifles. I cannot say if there is a wider range available or not but even then, why do you prefer it? Just because of the 2 explanations above? Just asking.
Other reasons I prefer picatinny are:
1. It's more secure, although for a PCP, it's not as important unless you're banging it around in the woods or PRS/NRL22 competitions.
2. Again, there's a wider selection. For me personally, I take an overkill approach when it comes to airguns. Scopes are getting bigger and heavier. Quality scopes rings in picatinny are available in 34mm, 36mm, and even 40mm main tube sizes. Not so much options in those sizes are available for dovetail.
3. There's also scopes, thermal, and night vision optics with integral mounts that are available in picatinny vs dovetail. Also, many red dot optics, holographic sights, magnifier mounts have mounting bases for picatinny only.
4. If you really want high quality scopes rings, you'll mostly find them available in picatinny only.
5. Indexing. If you decide to do maintenance on your airguns, removing the scope is something you might have to do. When installing it back on, having the available slots with picatinny is much more precise.
6. Switching between optics with picatinny QD mounts is easier and precise. With my Leshiy 2, I switch between a magnified optic and a red dot with return-to-zero picatinny QD mounts.
There might be a few more advantages with picatinny that I might be forgetting but this post is getting long. Yes, dovetail looks cleaner but I'm an overkill kind of person. Hope this clears it up on my preference.
