I think it's the only component that I wouldn't know how to adjust/fix on my new bicycle, where previously I feel I could have handled everything (but it was a simply fixed gear bicycle).
Hardly "so expensive no amateur will afford them".
What expensive specialized tools would you need for hydraulic brakes? Maybe I haven't kept up with very latest models, but I've had hydraulic brakes on my bikes for nearly 20 years now and I do all my own maintenance. I haven't needed and don't have any expensive specialized tools for it.
I had to bleed the rear brake of my bike because when I was changing the pads discovered one was much worn that the other, and in the process a piston went out and the liquid leaked.
Once I could got the necessary stuff it was a fairly easy process.
Recently changed oil on mine had a bit of help and it was tricky/finicky but nothing impossible.
As mentionned in another comment, there is so much information available online.
I would personally say that a fluid bleeder and seal picks/hooks are pretty universal tools, handy to have around. Hydraulics have been around for decades too, it's a very ubiquitous technology.
Even for crimping lines you can get pretty affordable tools, but I will concede that crimping new hydraulic lines is probably not that common of a task around the house.
An amateur can't afford a $50 bleed kit?