I have Plant with Allison. Nothing negative to say about that nor Page, just making reference to age. Three Dog Night was a sort of bridge for kids of tight-assed parents that thought the Kingston Trio was "da bomb". It was like a building block. From that listening to "Close to the Edge", a concept album precursored by the Moodies (most of their work pre-80's), was like the difference in football then and now. The Moodies are significant also for employment of the Mellotron (pre moog synthesizer) with orchestrations while paving the way for Yes, Alan Parsons and much of Pink Floyd post Syd Barrett which was something very different.
Chicago made a name for itself early on with brass ala Blood, Sweat and Tears and was a nice change of pace in style before turning to commercial ballads of Cetera, which I must say I like. Rolling Stone cronies comprise the RRHOF in Cleveland, not musicians. In my era, everyone had Bread (Gates as to Cetera) and kids loved the Moody Blues. Hell Justin Hayward alone could stand on his own as a lead for many, many groups that fell out of sight. I'm not saying that he is McCartney or Lennon, but he would have stood in nicely I would think.
When I'm not shouting at kids to get off my lawn, I try to keep current in music among other things. But whenever I hear something today I can generally parse the melody from something I have heard before poorly disguised as something new. Van Morrison says it right I think when he states that everything's been done. So when a friend of Country Western asks me to listen to something new I might denigrate the artist a bit by calling him "Peach Ice-Cream" but I do it moreso because of Hank's contribution, not the newcomers lack of originality.
True ABBA had mega-sales worldwide but in the grand scheme of things their true contribution might rate alongside of Nirvana which was shortlived but very good all the same. I might like Robbie Robertson's version of "Broken Arrow" simply because of the coarseness of his voice over Rod Stewart's version which is more marketable, but Robertson has produced much more music of various artists than the one or two big tunes a year that Stewart has made a living from over the decades that he could not pen himself.
There is no denying the commercial appeal of some of the above mentioned artists over others; or Notre Dame, Southern Cal or Alabama's brand name in football to the masses over Auburn, which is, to date, more regional. Suffice to say we know what we like and that the accolades and titles are more of a popular politicized nature. There are recruits that still claim that they know little of AU.