But the only reason Billings was allowed to replace Foakes was because Ben tested positive for Covid, not because of his injury. It's not that long since subs were first allowed at all.
For out field players, yes. But there's always been leeway with wicket-keepers. If the opposition captain allowed it, a team was allowed to replace their wicket keeper pre- the days of covid or concussions subs. It's just that they weren't allowed to bat (which they can do as a covid or concussion sub).
