I mentioned this on the sibling comment, but I've honestly never had any issues with drivers/hardware support with Linux on laptops ( with the exception of putting Linux on an early 2015 Macbook shortly after they came out, which had a new wifi card model, one of those new-at-the-time force touch trackpads that used different drivers, etc.). That being said, I only started using Linux in 2012, and I know that things used to be much worse in that regard.

As for technical support and training, I can see that being useful in an enterprise context, but again, I honestly can't see the type of people who want to single-boot Linux on their laptop being interested in support and training from Dell, HP, etc. It's been my experience that by the time someone is comfortable enough to use Linux as their sole OS (which many people don't want to do despite being comfortable enough due to needing Windows for other reasons, like gaming), they aren't really going to need or want any tech support from an OEM.