In a developed economy, maybe barely. Depends on the monitor, and what's wrong with it. If you're good enough at soldering, and it's just a capacitor in the power supply issue, and the case isn't going to fall apart when you open it, sure. But if you have to hire help, or replace a module, probably not.

In places where skilled labor isn't going to billed at $100/hr or more, then there's more you can do ... I don't think it's worth replacing a panel if the panel (or its wiring) go, but you can replacing modules likely makes sense, if you can source them; maybe some light module repair too if it's just cold solder joints need rewetting.

As for why? $ per benefit.

I had a pair of Samsung 204B screens I liked. I didn't see dollar per benefit in upgrading from 1600x1200 4:3 to 1920x1080 16:9.

They went funny, I obtained a capacitor, pop the back off, unsolder and solder new cap, put the shell back on. Job done. 20 minutes per screen because man, am I bad at soldering...

They worked happily for another 5 years each. Until society got well past the 1080p rut and into proper 1440 and 4k etc screens which were actually worth upgrading to.

Edit: make shorter

The panel? No. The panel was the singular expensive part, and the cheapest and most available way to get a new panel is usually to buy it in a retail box with the rest of the monitor already wrapped around it.

The backlight tubes? Surprisingly enough: Yeah, if a person really wants to do that, and if the display uses fluorescent backlight, then sometimes the tubes are replaceable. (LED backlight is basically ubiquitous on newish displays and is, AFAIK, kind of a non-starter to dig into repairing. But it might be do-able by swapping bits from a broken panel if one were sufficiently motivated.)

Power supply bits? Sure. It's just a power supply, right? Power supplies are often repairable or replaceable. (I've repaired power supplies in LCD screens myself, and I'm pretty lousy at component-level troubleshooting.)

Broken connectors and switches such? Very repairable. (Difficulty depends a lot on how much, if any, of the board also got destroyed, but generally speaking hot air soldering is a lot easier than it looks like it should be.)

Mechanical issues, like a wonky stand or broken housing? Often repairable. (The screen I'm writing this with has a cast zinc base that broke due to metal fatigue. I've fixed it twice: Once with two part epoxy, and a second time by adding CA glue when the epoxy's grip on the zinc failed.)

I have no idea what to do with it though and tossing it feels wrong.

Of a bog-standard 1080p 60 Hz monitor, perhaps.

I have a 4K 144 Hz 27-inch monitor I bought in December 2021, and paid nearly $850 for. These monitors still aren't a commodity good, and still end up being pretty expensive.