I’m not sure enterprise computing was ever based on open/general tech. In the 80s everything ran on closed-source for-pat Unix systems and big-iron proprietary mainframes. In the 90s that shifted more to Linux but increasingly companies would buy “appliances”, which are pieces of general purpose hardware combined with specific software. Those appliances were never meant to be opened or toyed with and the hardware lifecycle was based on the software lifecycle. If the software was discontinued, the hardware was thrown out as well. Appliances are still very popular today because again enterprise companies like stability and predictability.

An appliance is the ultimate lock-in and enterprise companies LOVE them.

Not just regrettable in a philosophical sense, but in a real, break-fix, operational speed, meeting multi-million dollar per night, getting-shit-done-for-real bottom-line sense. There is a direct correlation in observability in open and closed tech components of a stack. If you have the tech talent to dig into open stacks, break-fix resolution is faster with more granular traceability (and observability depth is unmatched), your team's understanding of the data and process models is more thorough, you gain a better understanding where the design limits lay or at least their directional value, and you have a better overall sense of control over the solution.

That "if you have the tech talent..." qualifier is the big one, though. I see very few companies who recognize how to attract and retain that talent level. IMHO, out of the more than 200 companies I've consulted at or sold deeply enough into in the sales cycle to see enough of how their sausage gets made to form an opinion, probably no more than 1:100 do this. So we end up here, where most companies are content to hire well below that level, buy closed tech stacks, and then play support-tag while users sit unhappy. Plays well politically, but it's a mess for delivery service levels.

As a business you need to decide what your core competency is and play to that. If you're a food distribution company do you really want to hire staff to "dig into open stacks" or do you want to just call the vendor and let them sort it out?

The reason enterprises can't hire that kind of talent is because they don't want to. The reason they can't retain that talent if they do accidentally hire it is because that kind of break-fix resolution

1) doesn't happen that often so the people get bored

2) is frowned upon by management because those people have actual jobs to do

and

3) is the entire reason they pay a support contract to their vendor

And $50k/yr in support costs is a lot cheaper than hiring the world's best DBA, world's best Linux resource, world's best Java programmer, world's best infosec analyst, world's best architect, world's best SAP resource, the list goes on and on.

The job of enterprise IT isn't to be the best at anything, it's to be stable and predictable.

Started dealing with computers since the mid-80's, I never remember big corporations being big into any kind of "open", beyond standard specifications like X/Open and similar.

Even Linux's adoption was more with not paying UNIX licenses than caring about any kind of openness.