I have to re-state the obvious applicable maxim to everything I've read in this thread: "Your mileage may vary".
I've owned a Gonset GSB-101 amp (the one matching their GSB-100 ssb transmitter, and containing the very popular four 811A's in grounded grid configuration). Until I changed out the electrolytics a couple of years ago, it still had the originals from 1958 running in it without problems. I still have those caps.
Some newer gear is "snake-bit" from the get-go, like the Yaesu FT-100 mobile hf radio with all of its grounding and weird RF problems. The later "D" version and the current FT-891 are much better radios with excellent functionality and longevity. Yaesu learned from its design errors of the past, but early adopter hams were stuck holding a "bag" of "you know what". (No buy back program or discount for a trade in of a carcass.)
I bought an IC-706Mk2G brand new at Dayton in 2000 and used it without problems for the quoted "20 year period". Then it developed an 80m-only band relay chatter after attempting to transmit after an hour's warm up. I tried to fix that problem and made things worse (no xmit at all) and sold the radio for parts.
(YES, that "20 year lifetime" estimate is prescient!!!)
Yet I bought a Mk2, no "G" version as a parts radio in 2015 and managed to bring it back to full functionality, working on it evenings for a couple of months. It still works and I like it a lot. But I learned a few things by both experiences...
Parts going obsolete are your worst enemy. The G radio had one or two relays bad on its BPF board. They went obsolete and NLA (I looked really hard for some) back in 2019. This was 2022. I had equivalent relays from my non-G radio, but they were same spec's with different manufacturer and different footprint. I cross-wired one of these into the space where the suspect relay was. I'm betting it worked, but since all bands now were dead on PTT transmit, I think I fractured an internal runner in a flex cable. I got tired of the fight and gave up.
...and YES, aftermarket relays were available for the non-G radio, but not ones for the "newer" G model's BPF board. Remember, you have no control over "what gets obsoleted when". This can make a newer SS radio into the "prettiest car in the junkyard" well before an earlier vintage SS radio. Parts availability timing is real crapshoot.
When the non-G decides to eventually poop-out, it will be sold for parts like its younger predecessor.
The fire in that Japanese mixed mode custom IC plant in October of 2020 made a lot of service parts into "unobtainium". This is why Kenwood discontinued the TH-D74A talkie, Icom its ID-51A and 31A, and Yaesu its FT-3D's. I really like my Kenwood, but if it ever dies, I will not try to revive it. I'll just buy the current manifestation, if not from "brand K", then from someone else. It's also why high end hf radios like Kenwood's TS-990SAT were recently obsolteted. (Kenwood wanted to keep their cache of NLA parts inventory to cover warranty returns, and not use them up in ongoing manufacturing of a low volume model.)
The smaller, discrete semiconductors usually get obsoleted by Icom after about 7 years. I was only able to get the non-G 706 going again by sourcing Chinese parts from Amazon and eBay. If it was the main uP in the radio, I'd be screwed royally with owning a cosmetically nice door stop. Old boat anchors don't have this problem. Most of their parts (including power transformers) can be Frankensteined from other equipment or substitutions made and shoehorned in. It may not be pretty, but a lot of sins disappear once the cabinet is put back on.
Don't even get me started on SMT. I worked with it a lot in my former engineering career and know what I'm doing, but it's very true that ham equipment was built like consumer electronics. I'd swear that I would just "show my soldering iron" to some radios from a distance and their pcb runners would start to curl or float away. Boat anchors never had this problem, but their technology (albeit fun to work with from a nostalgic point of view) is not what I'd want for my "daily driver" rig. Many of their pcb's won't survive more than one repair cycle, no matter how good the tech you are.
So, unless your problem lies with obsolete, NLA parts...really no radio is "unrepairable". It's just a question of how much time and money one wants to expend to get "the old girl running again". If it pleases you, then do it...but know when you need to give up before your widow needs to send it to the "great ham radio equipment landfill".
Resurrecting dead gear, whether old or new, is a fun ham radio sandbox in which to play...but when it ceases being rewarding, you have to know when to quit...and move on.