There's no point to the "new tab page", it would be better to have a popup to type the URL into and then hit "Go" and have that open a new tab. For me it's really just a distraction. Why would I open a new window/tab if I didn't know where I'm going?
You can have it blank or you can have Firefox recommendations. Those are your options.
https://i.imgur.com/U13r7pG.png
This resembles a dark pattern to push users toward Firefox recommendations, a moneymaker.
Correct. I am ignoring that fact because I don't want new tabs to display "Firefox Home" and I am not interested in customizing what it contains.
I want new tabs to display an HTML file that I made myself. Firefox previously allowed doing so.
The replies that suggest using extensions to re-enable the disabled functionality probably have not actually tried doing so. What those extensions do is load the "Firefox Home" content, then (as if on page load) redirect to whatever you set as your custom new tab. Which is just wretched. I could have typed the URL faster than that.
And on the subject of pushing core browser functionality into extensions: Why are things like Pocket, Firefox Sync, Hello, and the like integrated / bundled with Firefox but the ability to set a custom URL for new tabs requires users to install / trust a third party extension?
See also: The deplorable state of "Classic Theme Restorer", another case of "Users who miss the disabled functionality can just install an extension."