Once or twice a day, I notice a visual artifact that I perceive to be in my left peripheral vision, and of course I sometimes need to move my head slightly to see something, but being able to see clearly at all distances with relative ease is the exact opposite of “practically useless” IMO.
I'll defer to your judgement re optical properties, but I want to offer a counter-anecdote about practicality.
I've had myopia and have been wearing negative diopter glasses for over half my life. I've never needed vision correction for reading. This is not an unusual combination, and if you want a celebrity example, watch some old Apple keynote videos with the late Steve Jobs, who would repeatedly lift his glasses to read something on the phone in his hand. This "works", but can be inconvenient in some situations.
A while ago, I started thinking about progressive bifocals. Cursory web searches told me that my particular combo was impractical. My optician didn't see a problem, so I decided to trust him and got a pair made. The TLDR is that they work for me much better than the old ones. There was a period of adaptation. Going downstairs and looking at the floor/ground were a bit disorienting for a while, but i don't notice it any more. Switching between the monitor and the phone or paper in front of me works, which is why I wanted the bifocals in the first place. I only use the old glasses for watching TV, probably meaning that my TV-watching posture sucks, but fortunately I don't watch a lot of TV. I still take off the glasses for sustained book reading.
Traditional bifocals and progressives are different beasts. The hard outline on traditional bifocals means you get essentially two different lenses, both able to function as intended. The soft blend on progressives means you get essentially one big blurry lens that does not have well defined properties anywhere.
That seems to be exactly my experience with them, stated very succinctly. I've had these about 9 months and I'm still struggling with the ergonomics daily. I think I made the wrong choice.
I am near-sighted overall and have needed distance glasses all my driving life. I got progressives last year and driving is safer now as I have a small area that I can use to clearly (and quickly!) read the instruments, the radio (read: map), defroster controls, etc.
In my case, not having multi-focal lenses was prioritizing convenience/laziness/cost over safety.
The impact is a lot less than you may expect. Brains are ridiculously good at filling in incomplete information. For example, did you know that you have a roughly sun-sized blind spot slightly off center in each eye (where the optic nerve attaches)?
Now imagine needing to switch glasses to read your dash. Inconvenient and unsafe!
And yet I know many people who use them and love them. So?
The good news is that multiple glasses have never been cheaper or more accessible, so progressives are entirely a choice.
That's a fine argument, which I accept. Not the same as "practically useless", which was the original argument.