Air gaps and data diodes are mostly impossible or useless for regular commercial settings. That means your daily servers and VMs. Even tcp requires back and forth. I don't even know if satellites broadcast unidirectionally and just hope base station picks up on it. Surely just shouting into the void is never "communication". It's like receiving FM radio. That's useless for most companies. And if that is already useless, true air gapping is even more useless. Why would I run something offline in the age of the internet? And bypasses are always put in to make things more convenient, defeating the purpose of having the measure in place in the first place.

Thus there is only a very small segment of industries and people that utilize these things, and with it becoming a niche, it gets forgotten. I won't be surprised that the only users are small part of government and defence.

A more useful thing will just be what homelabbers use - if you're lazy cloudflare tunnels, or if you put in the effort, corporate VPN and DMZ and ACLs and VLANs etc. It's already well established, it's not a lack of knowledge, it's a lack of effort.