Robertson was essential to The Band, especially as a songwriter. When they regrouped without him (Jim Weider taking his place on guitar) it was not remotely the same. Richard Manuel never got back his songwriting mojo, and the magic just wasn’t there. Like all bands, they had run their course, given all they had to give, pretty much in those first two, perfect albums.
The Band albums after the first and second had scattered good songs (the duet between Manuel and Van Morrison on Cahoots’ "4% Pantomime" is a gas! Northern Lights-Southern Cross’ "It Makes No Difference" is utterly majestic.), and their live album is about the best I’ve ever heard (as is their live album with Dylan, Before The Flood.). On Moondog Matinee they created some very interesting versions of old songs. NO other band could have created that album!
But as far as the level of musicianship in a Rock ’n’ Roll band, they really raised the bar. They played like studio musicians, their only competition being the house band at Fame Studios in Muscle Shoals (The Swampers), Booker T & The MG’s, the Motown guys (The Funk Brothers), The Wrecking Crew (Spector’s L.A. studio band), and the Nashville players Dylan went there to record with starting in ’65.
If I go "overboard", I’m not alone. Eric Clapton’s reaction to hearing Music From Big Pink was to disband Cream (at the time the biggest band in the world), and go to West Saugerties (the location of the pink house) for a coupla weeks, waiting to be asked to join The Band. It finally occurred to him that they neither desired nor required his services ;-) . Every good guitarist I knew in the Bay Area traded his Les Paul or SG for a Telecaster, their Sunn, Marshall, or Fender Dual Showman for a small combo amp (the Fender Deluxe Reverb being a particular favorite). Gone were the long guitar solos, in was songwriting, harmony singing, and ensemble-style musicianship (playing for the song). The Band completely changed what was hip.
But of course unhip was much more commonplace. As the above was going on, Led Zeppelin, Black Sabbath, ELP, Elton John, Aerosmith, and all the rest took over Rock. There was Creedence from the East Bay, and The Doobie Brothers from my hometown of San Jose, and then Fleetwood Mac (when fronted by a couple more San Jose residents, Lindsey Buckingham and Stevie Nicks. I saw their SJ garage band Fritz live in ’68), and lots and lots of Blues-based UK bands. Hundreds, maybe. Ugh (as Sonny Boy Williamson said to The Hawks when they jammed together in ’65, right after he returned from a UK tour with promoter-provided UK bands: "They {the UK bands} wanna play the Blues SO bad. And that’s just how they play it." One of those bands was The Yardbirds, featuring Eric Clapton on guitar ;-) .
By the time things had gotten REAL bad (mid-70’s, right before the appearance of The Ramones), everybody I knew was doing what Dylan had done with The Hawks in the basement of Big Pink throughout all of 1967: follow the trail of music back to before Elvis Presley walked into Sam Phillips’ little recording studio in Memphis. We discovered Rural Blues, Urban Blues (Howlin’ Wolf rules!), Jump Blues, Big Bands, Western Swing, Hillbilly, Bluegrass, Folk (including it’s English/Irish roots), Tin Pan Alley, and some of us Classical. But we also learned there was a lot more to early Rock ’n’ Roll than just the big names: Rockabilly! The Johnny Burnette Trio Rules!! Listen to their version of "Train Kept A Rollin’" to hear how bad Aerosmith’s version sucks.
Would there even be the Americana Music scene as we know it had there been no The Band? I don’t think so.