Earlier quoted context omitted.
For 2 larger projects I'm on, I'm both the developer and a user: on a regular basis I use the software myself. And not just for one-off tests. I really use it the way other users use it. This has provided rather deep and interesting insights in software development for these particular products and in general. Or in OP's lingo: not a lot of potential for insanity at all. Because any new idea immediately gets regarded…
In my experience, this is the only kind of software that ends up not sucking. If development is not driven by users in a very intimate way -- like being one and the same person -- then you routinely end up with necessary features only half working or splitting essential information across multiple screens or dialogs. Eating your own dog food is essential to rising above that, because only that reality will overwhelm…
Huh? Web browsers are still laughably bad even after all these years. They are engineering marvels, certainly, but using them leaves a lot to be desired. I cannot imagine anyone would voluntarily use them if the ultimate function was equally available another way.