Yes, mocked through late 70s through mid 80s during the Liverpool dominance from Bill Shankly to Bob Paisley, from Kevin Keegan to Kenny Dalglish. Yes, they won most of the trophies during that era.
However, the true test of supporters come during these downtimes. Where were Chelsea fans in the 80s (rampant today)? Where are Newcastle United fans now (rampant in the 90s)? Only left those in London and Newcastle, local fans, no worldwide support once they stopped hitting the tops. Manchester United is household name worldwide and their jerseys are bestsellers original or pirated worldwide for decades whether up or down.
I'm not saying winning trophies isn't important. It is, but winning, not buying.