This is basic editing functionality, a core part of the purpose of the application. You can call being able to edit a score "a feature," but it's hard to imagine what is more fundamental to it.

What alternative open-source, well-maintained, GUI-based engraving software that features this "basic editing functionality" would you recommend?

The score can be edited just fine, though not in the way you're used to or prefer. It doesn't make your request or others' invalid, but it's simply wrong and preposterous to suggest that MuseScore doesn't allow scores to be edited.

An executable file in /usr/bin can be edited just fine, just not in the way you'd prefer. So much so that certain licenses can legally prevent you from redistributing that binary without source. How easy something is to edit matters --- so much so that legality can hinge on it.

I’ve been using it for many years now and I’ve never found myself wanting to reorder notes by dragging them around. The difficulty (among others) is that dragging is reserved for small visual adjustments. If it were also capable of moving notes from one beat to another, people would find themselves trying to make a visual adjustment and suddenly moving their note to the next beat over. It doesn’t make any sense. Use note input mode instead of the mouse and you’ll have an easier time.

> I’ve never found myself wanting to reorder notes by dragging them around

I cannot imagine using a program like MuseScore for anything other than composing original music, whose content is not known at the outset.

Pretty much everyone who defends the MuseScore UI turns out to be more of a music typist. (And, sure, that is an entirely legitimate, necessary activity in professional music.)

"Oh, give it a few weeks of learning, and you too will be transcribing existing music (for your whole orchestra even!) in a clean left-to-right pass whereby you don't have to go back and do anything more complicated than adjusting a wrong note pitch."

I’m not sure I understand what you’re saying, but I have been composing original music—not transcribing or “typing”—for many years in MuseScore. I do not use the mouse for note entry. I cannot imagine wanting to use the mouse for note entry. The computer keyboard in note entry mode is so much faster than clicking around with a mouse.

Do you have any videos of you composing, or else someone else doing same using a very similar workflow?

There must be some reason you are unimpeded, such as having excellent grasp of music notation? Like if you hear a syncopated rhythm in your head, or tap it out, do you know the exact rest values you need to insert to achieve it?

If I'm doing it, I need to be able to take a stab at it, play it back, and easily adjust it as needed, like add another sixteenth rest here, and delete one there.

> Like if you hear a syncopated rhythm in your head, or tap it out, do you know the exact rest values you need to insert to achieve it?

Yeah, if I can hear it in my head, I can write it out, at least for the genres of music I’m likely to write. I used to do it on paper, so the playback function is nice to have but I don’t need it to know I have the notation right. I’ll fairly frequently make a typo in note entry mode, like forgetting to switch from quarter notes to eighths or whatever, and have to go back and change a note duration, but I don’t get in situations where I would need to insert a sixteenth and make the rest of the measure reflow or whatever. Not sure if that’s what you’re describing.

As an alternative to MuseScore, I'd recommend moving to a monastery, where you write music by candlelight with a quill and inkwell, while wearing a hair shirt.