It's not even about player attitude and enjoyment. - it's about doing what you're good at.
Mourinho was asking his team to do things they weren't good at. Ole is asking them to do things they are good at.
That's management 101 whether you're building a football team or whether you're running a company.
When Mourinho came in he spoke about growing youth, scoring goals, playing attacking football, and winning trophies. He refused to adapt to any of those things. Personally, I commend the board for not doubling down and backing him further or else United truly would have lost all remnants of its roots.
The only mistake was hiring him in the first place.