Rolling up all the YC single-feature SaaS business into a single sales org and providing an a la carte set of solutions to partners would make a ton of sense.
I guess that is the theory behind SaaS.group and its ilk.
IMO, the reason many YC companies struggle with enterprise sales is because it's generally much harder than PLG, with long sales cycles and delayed feedback loops. It was definitely a learning curve for us!
An underrated challenge with enterprise sales is often that customers often misguidedly believe that 1) they can build it themselves, 2) they are worried about your companies ability to "scale" to their needs, and/or 3) the customer wants to "own" that responsibility for personal/political/career reasons.
Sales is hard for everyone including Azure, AWS, etc, just gotta keep grinding at it.