This is an issue ive had with wow for the past 14 years and mention every so often. Guilds are actually kinda antisocial. When i played vanilla i was strictly pvp. Guilds were an inpediment to recruiting players for pvp activites because some pvpers were in a raiding guild and couldnt just gquit and join a pvp guild. As a result, i resorted to not have a formal guild that used in game guild tools. I had a mish mash of people from various guilds and we used a private channel for in game chat. It was clunky and awkward and the problem was guilds.
What if they did away with guilds and reimagined them as google-style circles. You can join multiple circles at the same time and they overlap. This would allow you to join a raiding guild, a pvp guild, a leveling guild all at once as each would be its own circle.