I will hear many things against Boris Johnson, but the roots of the Tory malaise were there long before he turned up. They've been good at getting power still, sure, but they can't stop turning on each other and self sabotaging when they have it. The last time they were in government themselves and able to cohere round a leader for any sustained period was the late 80s. The leaders since then have all ended up hostage to the batshit wing sooner or later.
Johnson has obviously been balls deep in the instability since 2015, but the party were just the same in the 90s.