That had been going on at City (and other clubs) for years..!
I still remember vividly Sheffield United at home in 67-68. I met the Old Man after playing school footy that morning and we went (unusually) into the Platt Lane stand. It was rammed in there as City had had a good start to the season, which ended with us winning the title. I recall saying how the part of the Kippax where we usually stood was really full too, along with the Scoreboard End, which was full of Blades fans.
After we won 5-2, all the way down Lloyd Street back to Hulme I speculated that we must've topped 45000 that day but the Old Man was laughing, saying 'Uncle Albert (Alexander) won't be letting the taxman know that..' Next day in the 'Sunday Express' results page.. reported attendance 32000..
I swear they'd still be doing it if it wasn't for this brave new world of social media followers/clickbait that clubs have to sell themselves to nowadays..!