I've never had a failing screen backlight, but since my original post in 2016 the Probook 450 is still going strong, not had to replace anything in it, it doesn't get "heavy" use, but it gets used a fair bit.
Personally I have always used Dell for my main machine, be it desktop or laptop, I have a Dell XPS 17 which is circa 2011 which is still going, had to fix the screen hinge, a common fault with this laptop apparently, but not replaced any components inside of it, in fact, it's still running the original install of Windows 7, that has a 2nd gen Intel i7 NVIDIA GT555m chipset, and I also have a Dell G7 with a 9th gen i7 and a NVIDIA RTX2070 chipset, had it about 4-5 months, and it's running amazing at the moment, hopefully with its 64GB RAM it'll last till the next decade and be able to run everything I throw at it like the XPS.
I've had all sorts in the past, Acer, HP, Samsung, Toshiba, and Dell, apart from the Dell's (even got an old Inspiron running XP Media Center, new HDD, new batt and new fan costing a whopping £30 all in (got HDD on auction on ebay, came wrapped and disk tested OK) and the Toshiba (i5, stock Intel graphics) they have all failed in some way or another.
I replace a fair amount of screens, but that is due to people managing to sit on them or shut them down on something, missing keys from keyboards, not much else "users' fault repairs".
I only go by my own experiences so other peoples experiences might vary.
Maybe it's because HP laptops are the ones that are the cheapest and mostly available everywhere (or they are here in the UK) that people just go and buy cheap and then they fail, a £300 HP isn't going to be built as well as a same spec £600 Dell or Acer, you pay your money you take your choice.
My old XPS was £1300, my new G7 was £1600, the old Inspiron was £800 all 17" screens but the Inspiron wasn't a "gaming" machine, where as the G7 and XPS were sold as such, although the GT555m will play games like GTA V on low settings left the game scene behind a few years ago now, it'll run all my old titles like Unreal Tournament, which I prefer to play than some "modern" titles.