I disagree - on paper sure they would, but at the end of the day the UK is the ≈2nd biggest economy in Europe (UK and France make up 2nd & 3rd and who is bigger changes every couple of years), unlike Georgia or Moldova or whoever else where their joining is barely noticeable.
That means that the EU is more likely to want the UK to join, vs smaller countries wanting to join the EU, although it would be mutually beneficial of course - the UK would likely increase the EU’s power a little more than the EU would increase the UK’s power, but saying that hides the fact that it’d probably be a 10+% increase in both cases.
Of course the EU could make an example of the UK if they were want to rejoin, but if they were to look at it objectively then they’d most likely reach the conclusion that the negatives of making the concessions they made before are far outweighed by the additional collective power of having the UK as a member.