I don't think there are manufacturer's drivers anymore. Everything for my HP 9019 in the device manager says Microsoft drivers, including for the imaging devices. In the last few years, the printer manufacturers have switched to just doing the applications. The printers have got so much smarts on board, they don't need a computer to tell them where to place individual dots. The printers get fed a much higher level data, and they figure it out themselves. Hence pretty much anything can send a job to a printer now.Agreed most units will work with the unified driver but if you want / need full access to the unit it's better to install the manufacturers drivers.
Used to be a big HP fan having had LaserJet 3, 4, 4000, etc and various ink multifunction devices but was put off latterly by their software (bloatware!). Maybe they've "amended their policy" on their software now?
Currently mainly using an ancient Dell 1320n laser with unified driver and an OKI 363 multifunction with dedicated drivers. Really like the OKI policy with there being around half a dozen different pieces of software / drivers so you can be selective on what you instal whereas as HP used to be an all or nothing approach.