But times have changed; tinfoil is no longer made of tin. The stuff you use to shield your ham is actually aluminum foil, which has a lower heat tolerance.
The high temperatures of your oven floor can actually cause the foil to melt right onto that oven surface.
And you can’t clean it off.
We’ve had Warners’ Stellian customers spend hundreds of dollars replacing the oven floor on relatively new ranges because of this well-intentioned mistake.
Instead, aluminum foil-makers suggest you line the oven rack you’re using with aluminum foil rather than lining the oven itself.