For me, a piston is still a solution looking for a problem. I'm not sure if it was a byproduct of the solicitation that got us the SCAR or just timing, but I remember in the early/mid 2000s it seemed like all of a sudden a lot of manufacturers got together and were like.....we need to make a piston AR. Aside from the actual SCAR, I remember there were a ton of piston uppers and complete piston guns. If I remember right, SIG at the time was the most popular (and also had the worst trigger on the planet).
Places like ARF were climbing over themselves to jump on the piston bandwagon because they didn't want a gun that 'shits where it eats' and now wanted an AR platform that they said was more accurate but less reliable than an AK47/AK74 to now have the best of both worlds with a super reliable piston in the super accurate AR. This was also during the same time people bought their AR based on 'the chart', rumors of an AK having a malfunction were shouted down, and the mantra of needing to clean the AR from top to bottom if you even looked at it funny or it might malfunction just like it did in the 'Nam, were the understood truths.
Then after a while.....everyone.....just....kind of....went back....to shooting their DI carbine.
If I recall, the thing that stood out from testing the piston system versus the DI was that the piston system actually had its internal parts stay cooler over the same length of fire than the DI did. That translates to longer maintenance cycles. Never could find out if that was planned in the design or just a , oh hey look at this! kind of thing. But again, why change over an entire weapons platform because 'it runs slightly cooler' and brings really nothing else to the table. Any differences between the two in the AR platform are negligible and do not merit any kind of changeover. The only way a piston based design shows up is if the entire platform just excels regardless of if it has a piston or not.
With that said, I have a SCAR20. I also shoot DI guns 4-5 times a week and have never felt myself needing a piston.