The decision by a number of oneworld airlines (notably CX, QF) not to give AA miles for L fares means their flights are not usable for economy RTW tickets (unless earning no miles is acceptable to you) - let's hope MH does not follow their example.
You can earn AA mileage on QF L class fares (50% base miles - full EQP on earnings). S7 and RJ are rather more frugal in earnings, but do earn. Trans Pacific CX flights almost certainly have AA code shares as an option. It is the regional SE Asian flights and the European flights on CX that require creativity in selecting other carriers (or FF programs)
Happy wandering
Fred