However, at no point did someone as annoying as Ed Sheeran dominate the charts...
For political, financial, practical, and historic reasons, the "live" tracks were supposed to be rerecorded specially for the show. So often you'll hear a unique version on TOTP.
After about the early 70s it was damn near impossible to record and mix a single in less than a day. So what actually happened is that the TOTP producer responsible for the rerecording would be taken out for a very generous drink and/or lunch while the "session" was happening, and then they'd return to find that a master tape had magically been created in their absence, and not at all brought in by the band's manager, having already been recorded and mixed earlier.
It was a weird sleight of management that kept everyone happy.
Then the bands would go on and throw themselves around with no instruments plugged in. The vocals were often live, but everything else was literally just for show.
Debbie Boone? The Beatles before Dylan told Lennon that his lyrics suck?
Anyway, the issue with Ed Sheeran is that he appeals to the Tweeny Girls who are the only group still spending money on music. And, as such, the powers that be are going to flog him senseless until he stops printing money.
The issue is less Ed Sheeran being annoying than the saturation marketing reaching comical levels.
By that measure, older music was much better. Sure, the chart has flashes in the pan and bubblegum garbage in every age, but the difference in memorability between the Top 40 now and the Top 40 even 15 years ago is quite staggering.