Could you please explain what you mean by "physical backbone connection", as I can't think of a meaning that fits the context.
If you mean dealing with the physical dedicated servers that can be rented from Hetzner, that's what the person you replied to was talking about being not so difficult.
If you mean everything else at the data centre that makes having a server there worthwhile (networking, power, cooling, etc.) I don't think people were suggesting doing that themselves (unless you're a big enough company to actually be in the data centre business), but were talking about having direct control of physical servers in a data centre managed by someone like Hetzner.
(edit: and oops sorry I just realised I accidentally downvoted your comment instead of up, undone and rectified now)
No worries, easy to not foresee every possible way in which strangers could interpret a comment!
But I think that people (at least jwr, and probably even nyc_data_geek saying "on prem") are talking about cloud (like AWS) vs. renting (or buying) servers that live in a data centre run by a company like Hetzner, which can be considered "on prem" if you're the kind of data centre client who has building access to send your own staff there to manage your servers (while still leaving everything else, possibly even legal ownership and therefore deprecation etc. to the data centre owner).
What you're thinking of - literally taking responsibility for running your own mini data centre - I think is hardly ever considered (at least in my experience), except by companies at the extremes of size. If you're as big as Facebook (not sure where the line is but obviously including some companies not AS big as Meta but still huge) then it makes sense to run your own data centres. If you're a tiny business getting less than thousands of website visits a day and where the website (or whatever is being hosted) isn't so important that a day of downtime every now and then isn't a big deal, then it's not uncommon to host from the company's office itself (just using a spare old PC or second hand cheap 1U server, maybe a cheap UPS, and just connected to the main internet connection that people in the office use, and probably managed by a single employee, or company owner, who happens to be geeky enough to think it's one or both of simple or fun to set up a basic LAMP server, or even a Windows server for its oh-so-lovely GUI).
If you mean dealing with the physical dedicated servers that can be rented from Hetzner, that's what the person you replied to was talking about being not so difficult.
If you mean everything else at the data centre that makes having a server there worthwhile (networking, power, cooling, etc.) I don't think people were suggesting doing that themselves (unless you're a big enough company to actually be in the data centre business), but were talking about having direct control of physical servers in a data centre managed by someone like Hetzner.
(edit: and oops sorry I just realised I accidentally downvoted your comment instead of up, undone and rectified now)