Partially off-topic, but when I started in the hobby O-rings were all the rage for people who like MX-style switches, but I seldom hear about them these days.
O-rings worked only with OEM-profile keycaps with the right stem length and internal struts. Most enthusiasts (and some brands) use Cherry profile, and for those keycaps, the O-rings were too thick. Very thin O-rings (for dental braces) were used for a while, but those have been superseded by "silencing clips" (QMX clips, Zealencios) which dampen also the up-stroke. There have also been more types of silent switches since then that don't need external modding and which work with any keycaps.
But yes, I think those have fallen out of popularity because they soften the feel. Hard bottom out seems to be more popular now.
There have also been developments in the internal construction of keyboards: flex-cuts in plate and PCB, mounting styles that suspend the PCB and plate in damping material, and filling internal spaces with sound-damping foam and silicone pads. Those reduce reverberations in the case and thus noise without affecting key feel as much.
These features started in customs but you can find even mass-produced keyboards with them now.
I wouldn't say that hard bottom outs are more popular in the hobby (in fact the direction is towards softer plates like polycarbonate and mounting styles that are less harsh like the various gasket mounts, I think for a lot of people, it was the mushiness that came from using the o-rings that made it undesirable, kinda like why people don't like regular silent switches.
I still think there is a market for silents (that's why there was still innovation in those haimu silents which changed the stem to make it not as mushy) but the hobby moved in general away from silencing things and making things "thocky" or whatever kinda dumb term people use to describe sound now.
Also if you want silencing, I think a lot of people move towards topre now, with the type s and external aftermarket silencing options.
I reluctantly used a set when I shared a WFH office with my wife, on a full size gamer board with Outemu black (still have it under the shelves... turn off the rainbow LEDs and those boards just look like low-profile Filcos), but once I had my own space, it was off with the rings, then back to my 70% with blues, then on to heavy clickies.
Right this moment, I'm on a Model M, but my two daily drivers of late have Box Jade and Box Navy.