If I understand it correctly (as someone who didn’t really follow it) Eichel wanted this surgery from the beginning, but was arguing with Sabres management for about a year. Now he’s in Vegas, and Buffalo traded him because he was adamant about the surgery. He’s now expected to make a full recovery. My question is: why would Sabres management get rid of their best player in the past decade over something so trivial?

There was 2 surgery options, Disc Replacement (Eichels preference) and Neck Fusion (Sabres preference). The sabres did not want Eichel to get the disc replacement surgery as no NHL player has had that surgery before and as part of the CBA the team has final say on what surgery a player can get. They did not want Eichel to get something that they didnt know how a player would respond back on the ice too so they dug their heels in the ground and did not budge.

The relationship bw the team and Eichel was already strained before the surgery, the stale mate bw the surgeries is what ended it, it was the final straw for Eichel

If the Disc replamcent surgery fails, what happens is he gets the fusion surgery regardless, so I really dont know why the Sabres were so deadset against it. It hasn't been done on an NHL player but Football and MMA athletes have received it and made full recoveries.

Probably the best way I can explain it.
He already requested a trade before the injury.
The surgery wasn’t insured.
They wanted another team to take the risk, the surgery isn’t as risky but no one knows how Eichel will recover.
The ironic part throughout this whole story is the Sabres doctors that saw Jack helped create artificial disc replacement surgery.

TL;DR,
The Sabres being the Sabres

Basically the Sabres didn’t want to gamble on an experimental surgery. Not that it’s actually an experiment but a good way to put is how Marek said, no real MAJOR athlete has gotten it (just some fighters, and rugby players which isn’t a bad thing, very physical sports). So like if this goes well it could be the Eichel Surgery (like tommy johns named after tommy John).

As Eichel is going like have a case study on him from the medical practice world. Similar to McDavid; instead of getting surgery McDavid did that insane rehab instead of getting an invasive surgery and he’s basically the first guy to do that (Sportsnet has a doc on it if you wanna watch it just google it). So the Oilers stuck by McDavids side and supported his “experimental” recovery whereas the Sabres did not want to stick by Eichels side for his “experimental” surgery. In both cases they’re tryna to recover the best way possible but both recovery paths don’t have much of a resume. McDavids worked wonderfully, and Eichels hoping to follow that path. But the Sabres for some reason wanted no interest.

This guy said it best. Based off what was said in 32 Thoughts the podcast, It seems like the Sabres just straight-up wanted to be petty against Eichel because of how he requested for a trade last season, and they used the surgery as their excuse. Pegula's have 0 idea what they are doing with that Franchise, and its embarrassing to Sabres fans

1.) Beginning of 1st Covid season sabres tell Eichel they are going to rebuild.

2.) Eichel says if you are going to rebuild, then trade me.

3.) Sabres owners get offended. GM signs Hall to massive one year deal to placate eichel (and owners).

4.) Eichel gets hurt.

5.) Sabres owners still upset about trade request fight him tooth and nail over surgery.

6.) Trade finally happens.

He might start skating with Vegas by around Christmas and might start playing with Vegas after the olympics at the earliest

I’m pretty sure football players have had this surgery done as well.

It’s absurd to me that athletes in much more physically intensive sports have had the surgery and fully recovered and people are still concerned about how the disk heals.

The Sabres were insanely petty over this and they used the surgery as an excuse for why they treated Eichel the way they did. Him asking for a trade when they wanted to rebuild must’ve pissed off the owners.

Now I don't blame Eichel for wanting out of the SabresLand, and I don't blame Sabres for finally trading him,
Sabres are "hoping" that Tuch and the 6m cap saving which can be spend on a good UFA will help the Sabres starting next season. Then hoping Krebs and the first rounder can be NHLers. Yeah one great Eichel might be better value, but the Sabres thinking they can get many years of NHL control of four NHLers instead of just four seasons of Eichel starting next year.

Playing for the Sabres is a worse punishment then any middle age punishment imaginable

You might be right. But Eichel also did it himself. He was the one that signed an eight year contract. Not that I blame him wanting long time security. He knew the Sabres were a mess.
I respect Trouba and how he played it when he wanted out of Winnipeg. After his ELC, he signed short term so he could be a UFA in four years. Maybe for Eichel's sanity he could have done the same, though it appears to worked out for both Eichel and Trouba.