Here is a hypothetical question guys: Let's say that Shariar (TheSignalPath guy) built an active probe that works up to 13 GHz and started selling it for $100. He has the knowledge AND the gear to do it. The going rate for keysight is $1K per GHz, so this would be about $13K. What would happen? My guess is that Keysight would contact him and offer him a very generous amount of money to make him stop selling it What is your guess?
This is actually an easy one.
Companies pay for the brand name stuff from a few reasons
1). Support. If it breaks, you get it fixed or replaced fast. Down time in a lab costs money. Lots of it.
2) consistency. If you buy 5 of something from a big name, they will all work the same. They will also work the same as the one in the lab across the county.
3). Reliability. If you can't trust your measurements you are wasting your time. That includes having reliability over the life of the product, which is typically a long time for big name stuff
4). Lower risk. You have a much lower chance of having to justify purchasing big name brand equipment than "some dude on the internet". It's an easier business decision considering there are budgets for this stuff.
Of course there are exceptions and examples of big name stuff violating all that stuff. But it's generally the way it is.
Big name companies don't feel and pain for small shops and hobbiest buying alternatives. They are after the big fish.