I hate temporal mechanics too!
If we go by beta canon, Harry's a captain in at least two timelines and well on his way in a third.
And still an ensign in mine. I haven't found any reason to promote him yet.
But the information about Locarno I found shows that at least some writer did come up with something about what happened to him after he was kicked out from Starfleet Academy.
However, I didn't like that scenario either.
Being past the half-century mark, it's rarely far from my mind. And it's only going to get worse..
The only way is to fight it as long as possible and when that's impossible, pray for a quick departure.
No such excuse. This character's contemporaries lived their best lives, started families, had careers. The decision to eliminate this kid came because one, he was still in love with my protagonist; and two, I had no other character to pair him with, and conjuring one out of thin air a few years down the road is too deus ex machina for my tastes. Simply put, when a character can benefit a story more in death than they can in life, I will usually eliminate them.
Not an excuse for me, just my style of writing. If I kill off a character, then it's planned from the start, like it was with Stadi, Cavit and Fitzgerald in
Caretaker.
Considering that a full half of the series now has had nothing to do with the Klingons, maybe you should stop condemning a series you largely haven't even seen? Given the massive change in premise that the series went through in particular between S2 and S3, but to a lesser degree between S1 and S2, I think it's fair to say that if you gave up after six episodes then you're not really qualified to talk about it.
Just imagine using the first six episodes of TNG S1 to pre-judge S3 forward. Or DS9.
The first six episodes of TNG and DS9 didn't bore me as much as series like Star Trek Discovery, Star Trek Enterprise and NCIS Hawaii, all series which I've quit watching after about five-or six episodes.
If I find the characters boring and uninteresting, the series as too much doom-and-gloom or boring or annoying in common, then I quit watching. The same if I watch a movie I don't like, such as "Greenland" which unfortunately showed up on one of my TV-channels yesterday. I quit watching after half an hour.
Despite the teenage Ninja Turtles Klingons who I found highly annoying, I didn't like the characters in Star Trek Discovery and I guess they are still there.
The only series I really disliked but continued to watch up to the end was the horrible Stargate Universe and the only reason for that was because it became a joke between me and a mate at work.
I actuallt stopped watching that series after four episodes but started watching again when my colleague told me that he had fallen asleep while watching it. Then it became a joke, like:
ME: Do you know what day it is?
COLLEAGUE: It's finally Friday!
ME: And what will happen then?
BOTH OF US: We'll watch Stargate Universe! Our favorite show!
Then on Monday, we used to discuss how bad the episode was!

But that's the only exception to my rule of quitting watching if I don't like it.
Characters are important to me. I've been watching NCIS for 18 seasons but quit recently when some good characters left and was replaced by lousy characters. The series isn't the same anymore as the one I once loved.
Anyone should be permitted to watch or ignore a given Trek series, without judgment by any of us. Be that as it may, though, Discovery might rate a second look.
As for now, I don't feel like wasting my time on it. OK, the NNinja Turtle Klingons might be gone but the boring characters are still there and I guess that the 2010's-2020's doom-and-gloom (which unfortunately affects Star Trek Picard too) still might be the same. I rather re-watch DS9, TNG and the first three seasons of Voyager again.