No doubt slam is a more common element mixed into many (not just pop/hip/hop/electronic genre) more modern recordings, many of which sound very good, but only when the playback is up to the task.
Its noticeable in most well recorded CD from mid 90's on. That's about the time where I have read some fundamental standard EQ changes (for the better) were implemented in teh recording industry. ALso coresponds with the start of teh infamous "loudness wars". These days CDs are much louder (hence more "slam") so the game has changed. OF course many pop recordings targeting getting attention from the masses are overdone and are sonic atrocities in many ways, but many more are not and done quite well albeit at louder levels overall on average than in early years of CD.
So this gives recordings a bias towards "more slam" compared to many live experiences, but that'snot to say slam does not occur in live performances both acoustic and electronic as well, as noted above.
"Inefficient" systems will have more trouble delivering louder recordings with more slam well in general. EIther more efficient amps, more efficient speakers, or perhaps even both are the tickets to getting to a good place in regards to a playback system being able to deliver all the goods in any recording, for better or for worse.
Luckily, I am finding more sonically great moments when I listen to recorded music these days than ever before in my 50+ years, in recordings of all types both old and new. So hopefully, that is a good omen in general.
"Slam" done well has always been a sell point for many of the best "audiophile" recordings over the years.
Nowadays, its a lot more common, for better and for worse, and not so novel. You do not have to buy a special "audiophile" recordings in many cases to get it done well. Off course it is also often "overdone" as a selling point as mentioned. THat's entertainment! Nothing new there with teh entertainment industry overdoing something and even beating it to death regularly.
