The thing is, this whole Ryzen is smoother topic came up back in 2017, back when Intel's main 'gaming' line were i5's - 4c/4t CPUs, which were starting to feel the hit from games using more cores, and Windows using more cores for background tasks; inevitably causing stutter and hitches; most people's machines aren't anywhere near as clean as benchmarking machines, and Steve himself even made a video comparing clean vs non-clean/RGB software, and there were SPIKES. This was inevitably where the comments came from, you'd get a 8c/16th CPU or a 6c/12th Ryzen 1st Gen cpu fighting the average persons 4c/4th CPU, whilst running a busy, non ideal system. When stuff started firing off in the background, the Ryzen simply had more threads and cores to deal with this 'off topic' content so to speak. Steve forgets that most people do not run a machine objectively clean, they run it used with multiple tasks running in the background; in this case, the higher core and thread counts all start to make a difference. Not on average framerates, but on those spikes caused by background activity. Hell anyone who has been around long enough remembers how bad things like AV used to tank systems; this is just a continuation of this issue; cores/threads/io getting tied up by background processes; throw in more capacity and you hit those bottlenecks slower.
It's exactly the same reason as why many streamers found streaming caused lower framerate degradation on Ryzen CPUs, they had more cores and threads to allow the streaming to basically use a few cores whilst still offering the same number of cores to the game, therefore reducing thread/core dependency and sharing. Back in 2017, the Ryzen is smoother WAS true in many cases for many people, due to 'non ideal' software configuration and background tasks, and due to many people having 4c/4th i5s due to the 'i5s are enough for gaming' status quo at the time. They haven't aged well though by comparison!
Steve had a point with his video and topic, but he missed the mark with the exact point and comparisons being made. If he had focused more on the older comparative CPUs like the 4c/4th 3000-7000 Intel series chips, rather than the 8th ones and more modern CPUs, and on a less 'clean' benchmarking setup with suboptimal windows configurations and background tasks; he'd have been more on the point of WHY people had stated at the time Ryzen is smoother.