This was going on a couple of years ago, but you still can't assume that Dell versions have no adjustments. Regarding particular issues that were bugging my 9550 UHD (brightness flicker, black levels), there were times when a only a particular Intel video driver version released by Dell would play well with a particular BIOS version (and the two may have not always been the actual Dell version at the same time). However, this has not always been the case with the Intel HD video driver. In most cases, drivers straight from the manufacturers do work. Generally I don't think Dell is particularly careful and agile with BIOS, drivers and their issues, rather on the contrary, there are many open issues that go unsolved for months, years.

and eventually they just drop support for their older laptops, while the manufacturer will still push out new drivers and apps for their product.

So what's the point to use a Dell driver that is often half or 1 year old, instead of the latest Intel one that solves the users's issues ? There's no gain from waiting for Dell to catch up. Dell are just very late to the driver support party, and they have this terrible habit of changing version numbers to their own, making things very confusing. The release notes for Dell drivers are identical to the release notes from manufacturers. Dell doesn't seem to do any real testing or improvement of the manufacturer drivers.

Intel graphics control panel install