Your feature flag might be “SHOW_STRIKETHROUGH_PRICING_ON_CROSSSELL_OFFERS”; theirs is a bit mask macro to pick off the 5th bit from the 7th byte. (Why do they care? Because if they allow themselves to get fat and slow, a competitor will take the money.)
Roll-forward only, same day SLA is probably right for your business, but isn’t for a company that could have their systems dusting off $1M every handful of seconds that bad code is running.
Different business problems call for different technical approaches. You should no more adopt theirs than they should yours.
Reusing the RAM occupied by flags might be do-able in a clean way using guards like the structured enum in Rust, which permits unions (objects that occupy the same space) that always have the right type (i.e., the compiler has knowledge what is in there at each point in time). This mechanism could in theory be extended beyond type-safety to accommodate other contexts in systems programming use cases where memory usage is extremely important.
Rolling back code is another thing I have no tolerance for anymore. The only option we entertain these days is a roll-forward. If your software takes so long to iterate/build that you need to go back to and old version in an emergency, you need to review your languages/tools/frameworks/processes. We maintain a contractual obligation to our customers for same-day code updates (in cases of production/regulatory emergencies) because we have enough confidence in our processes.