Been there done that. Got the tee shirt.
While good support to customers is very valuable, trying to support a product that is decades old and shares nothing in common with current products is a plain waste of time energy and money.
It would require someone to search out all the documentation needed to make that one part, then you need to figure out the correct process to make said part, determine if you have material on hand or need to special order something, then try to find that one old jig/fixture needed amongst a building full of 100’s of such items for the right one. Then you need to be sure that the the complete fixture is there and nothing is worn out beyond use. Then you need to make time to insert this one-off semi-custom part into the manufacturing process.
By the time you do all this, that one 20 year old obsolete part will have perhaps cost you thousands of dollars and you still haven’t made the first piece of swarf. Imagine the shock and surprise that customer would have when they get the bill that accurately reflects the true cost.
I never have an issue with people preferring a different CAD package over another. For example: I detest Fusion 360 for various reasons even after spending a year with it. We all have preferences, work requirements, and even “vibe” better with one package over the rest. You need to choose the tool that works best for you.
What I do have an issue with is new users that try and have problems and immediately start whinging that “FreeCAD isn’t like what I know. And it needs to be like my favorite” Those are the lazy people that can’t be bothered to learn something new. And they should either expend the effort to learn or go back to whatever they were using or volunteer to code, (it’s open source after all). FreeCAD ain’t for you.
But if you have given FreeCAD, (or ANYTHING new in life), an honest try and you can’t get the hang of it or simply don’t like it. Well, that’s a valid and very fair reason to not use it.