All the FOSS offerings I can think of that are “too big to fail” have big corporate support

….

businesses don’t have that luxury. That’s why they use proprietary software.

Youre missing a few key things here.

• TONS of proprietary applications go years without work or effort
• TONS of proprietary applications/solutions get abandoned, leaving businesses and consumers to scramble for a solution.
• If the business relies on open source, they can contribute to that project.
• An open source solution also means continuity and the ability to fork when abandoned, proprietary solutions that are abandoned are just gone.

I wouldn’t put much agreement toward your argument for proprietary here, because I’ve seen (and had to deal with) proprietary solutions being abandoned with no workable solution available, especially as the current generation of proprietary solutions require a license server or other cloud-connected back end in order to work.

So when they get abandoned, its just over.

So no, this argument against open source for business has no merits IMO.