It's entirely the local property's option and a lot depends on the traffic the property experiences. In Asia, where many flights from Europe and NA arrive in the early AM, it is very common to strictly enforce the check-in time and to charge a hefty fee for an early check-in. No lounge, no pool, no nothing.
Unless OP called ahead and was told that the property would comp the extra service, the entire tone, e.g. that he thinks that there was a principle involved and suggesting that he ate more stale muffins than he otherwise might have in the lounge, is exactly why the property may have denied him in the first place !
Maybe someone who works at a property reading this will just stop comping lounge access prior to check-in !