Basically since the start of legion me and a couple of others have been in a few guilds (3 since launch) that have all had the same problem (All of the guilds disbanded/stopped raiding), lack of people to fill a full 20man team in order to progress the end tier content currently available up to date. And I'm pretty sure we're not the only ones feel this way about the current state of the end tier being locked to 20 players, when having the option to either run 10man mythic or 20man mythic would make raiding at end tier much easier.