It's ok, but it does drastically reduce its utility. Conversely, anything that can be put into smartphone becomes much more useful. It often makes a difference between just having a tool for some odd job vs. gaining a capability.

The reason is simple: you always have your phone on you, or near you. It's the most easily accessible piece of electronics, and - if you're storage limited - the last one you're likely to leave behind. There is a generic social acceptance of everyone having a phone on them (even if stashed in a pocket).

A FLIR camera as a separate device? I'm unlikely to carry it with me unless I have a specific reason, and people will look at me weird if I walk around with one. A smartphone-attachable FLIR camera? It's still a hassle to carry, there's a good chance I'll leave one behind (comparable to a bluetooth headset). A FLIR camera built into smartphone? On me all the time, everywhere, and always ready to use in random, unpredictable situations.

And yes, it's the same reason why regular smartphone cameras all but killed the compact camera as a product. Having a tool always on you expands possible use cases so much it offsets for suboptimal performance/form factor.

I recently found myself avoiding my phone for various reasons. At home I'd rather get work done (wfh) and I prefer to leave it at home when I go for walks. But my phone is also my camera, so now whenever I see something beautiful, I am unable to photograph it.

I read the other day that compact camera sales had dropped by 98%. I guess I'm one of the 2% that actually has a need for one now.

Grab something used with enough megapixels. I used an old Canon A590IS for years, even after I had a slew of Nikon dSLRs. I've found random compacts over 10MP for less than 20 dollars while thrifting. Completely competent images in day light tbqh. Low light and video capabilities are what really lags when compared to more recent camera tech but I've always limitation breeds creativity.

Just use airplane mode. I use it all the time, for this purpose exactly. Sometimes I am just not available - people have to accept that.