I had asked the manufacturer of my laptop if it supported 16 gb ram. For a long time I got no response from them. I decided to go ahead and try it. It worked with perfectly. Later I got a phone from the manufacturer, saying it doesn't support 16 gb!
Luckily I didn't ask them if it was SSD compatible(!). I had changed the internal 500 gb hdd to 240 gb SSD.
They probably want you to use the laptop as is and not run into any risk by making any suggestions.
(BTW, my laptop is not hp.)