Another good reason to be in stealth is if a company is built around a technology or idea that it hopes to patent but has not yet filed.
I think this exception can be generalized to pure technology development, even without the patent legal requirement of non-disclosure. It applies if you are developing a new technology that already has a known market; or an entirely new technology (in which case you are more an inventor or scientist than an entrepreneur). So, Edison got his light-bulb working well enough; Birdseye discovered the freezing rate for fish that worked well enough.
Of course, most internet startups are not pure technology. They're mostly about market development, and at best, applying technology to that new market.
A final factor is that, even for pure technology, it helps if you can discuss it with someone. So it's good to have a team. This is one benefit of working in a big corp lab.
I think this exception can be generalized to pure technology development, even without the patent legal requirement of non-disclosure. It applies if you are developing a new technology that already has a known market; or an entirely new technology (in which case you are more an inventor or scientist than an entrepreneur). So, Edison got his light-bulb working well enough; Birdseye discovered the freezing rate for fish that worked well enough.
Of course, most internet startups are not pure technology. They're mostly about market development, and at best, applying technology to that new market.
A final factor is that, even for pure technology, it helps if you can discuss it with someone. So it's good to have a team. This is one benefit of working in a big corp lab.