Yes there are - released by different record companies than EMI/Parlophone, that were based in different countries than England - not to mention those albums were of different musical genres to the Beatles.
Columbia did lots of long albums around that time such as Dylan as you said and Miles Davis - so what?
The Beatles weren't jazz improvisors, nor did they record 11+ minute stream of consciousness poetry set to music.
Speaking of Columbia, they also put out music by a band far more similar to the Beatles, than Dylan or Davis were - and THOSE albums just barely cracked the 30 minute mark. So which band was that? The Byrds.
Why were Byrds albums barely 30 minutes long while Dylan and Davis got 50+ minutes? Well for a start in the US, labels didn't want to pay for more than 11 song copyrights per album as that cut into their profits, so regardless of how short those songs were (about 2.5 minutes each) 11 songs was the set limit (with very few exceptions - in the Byrds case their first album actually had 12 songs for some reason, but 11 was their set limit after that, even when they had recorded additional songs during album sessions, as evidenced by the 'Never Before' outtakes comp from the 80s, and the expanded CD remasters from the 90s).
OTOH that 11 song limitation had little to no effect on Dylan (where he might have a 50+ minute album that contains as few as nine songs, given their length) and Miles Davis albums of that era would have needed to be double albums - if not triple albums in some cases - to even contain 11 tracks, given their normal track lengths.
So unless you can come up with some examples of other EMI/Parlophone acts putting out 50+ minute albums in the mid 60s in a similar style of music to the Beatles, then I don't get your point.
Comparisons need to make sense - y'know "apples vs apples" as opposed to "apples vs oranges".
It doesn't matter what Columbia was doing with Dylan in the US, if EMI was uncomfortable doing the same in the UK - plus how many 2.5 minute Beatles songs would it take to fill an album to 50+ minutes? It would take 20 songs/10 per side, just to get an album up to 50 minutes - never mind 50+ minutes.
The Beatles were in the business of recording sub 3 minute songs, 14 per album at under - and usually WELL under 40 minutes. With Pepper they for the first time ever not only broke precedent with one 5+ minute song, but TWO five+ minute songs, thus precluding the inclusion of a 14th song. If they had stuck rigidly to the length of their own last two albums (35-ish minutes) they would have had to leave a 13th song off Pepper as well.
George may have only got one song on the album, but it was the length of two normal length songs for the band at the time, so I guess that balances things out for George somewhat (at least as far as percentage of running time he had on the album, if not the amount of money he earned from the number of songs he wrote on the album).