Given that America has a literal 'Hamburger University' I'm not sure you can complain that a British university not having a pure maths department is some kind of dilution of the term.

It'd be illegal to call it 'Hamburger University' in the UK for comparison, as 'university' is a protected designation here and it wouldn't meet the standards for a university, while it does in the US.

(McDonald's does have the same training facility in the UK, but it doesn't claim to be a 'university' here or award 'degrees' like it does in the US.)