Kurohige has so many useful crewmates he knew what he was doing when he recruited them
Xebec tried to pave the way using raw strength. Seeking the strongest pirates around and feeding a DF Harald who is the strongest non-affilated king. Then he went to publicly antagonize the government
Teach almost certainly read up on Xebec's rise and fall to avoid repeating these mistakes.
>He's not building a crew revolving around strength only, he's building one that is also suitable for some kind of assassination mission (invisibility, cloning, teleportation, environment control etc...)
>He's trying to publicly establish himself as a government ally using Garp, to clear any suspicions of him aiming at Imu's throne + gaining access to something that normally he can't.
>Most important thing; He's actively scouting for Poneglyphs and Ancient Weapons, something we never saw Xebec do. Xebec believed gathering all the powerful people there are is enough. Gigabeard foresaw Imu's divine power or read the Harley text and deduced that old civilization powers are the only way to bring him down.