Principle does not equal lawful.
Remember, despite the fact you bought the cooktop, what you are doing is replacing the LANDLORDS property.
As a tenant you are protected from mischievous claims by the landlord. This means you are can’t be charged for fair wear and tear on items.
If I recall , earlier posts suggested to negotiate with the landlord about the replacement cost of the cooktop. The cooktop had already served some of its useful life, so it’s not worth it’s full replacement value.
But you were advised that that route was probably going to not end well for you, and an alternative was to just replace the cooktop.
Our tenants laws favour landlords, and landlords can play hardball, because they know that if they don’t renew you, or you decide to leave, there are many more like you willing to rent the property.