Various software was transferrable. For instances, both the original Sim City 2000 and the original Myst stipulate that resale or transfer are allowed so long as the seller retains no copies.

A EULA does not have to be correct. Tons of absolutely unenforceable clauses end up in those.

That's fair, the onus is on the seller to enforce them, but that doesn't mean you can completely ignore the EULA

(hint: the LA in EULA stands for "License Agreement", not Bill of Sale...)

What matters is that a physical release holds some value, as there is a resale market for it. Meanwhile, there is no market for „offline installers”.