I'm quite certain there are guilds that do what I and the OP are suggesting. Guilds that only lose once or twice a year and always only have 30-35ish sign ups.
They're deliberately targeting smaller guilds, in the knowledge they have enough fire power with those they allow to sign up, to hold firm and get through the whole defence.
I don't think they're 'out to get me'. I'm not angry about it or believe it's personal. They're just not playing how the gaming environment was intended. My whole life ethos is 'playing by the spirit of the game/rules', and they're clearly not. I don't think the very 'big' guilds do it, the rewards just aren't worth the hassle for the whales in this game.