Apologies in advance for the snark but let me paraphrase:
"It's not necessary to give your startup your complete attention to run it. I treated my shareware business as a part time job. Mind you, other companies that could focus attention on their competing products drove me out of business."
When MS and firefox built pop up blockers into their browsers it became very hard to sell a pop up blocker. I'd be interested to see you move into this line of business now and explain why your efforts are best spent swimming upstream.
To paraphrase you: apologies for being a tool, but I can't help it. I bet you "know how to make Twitter scale," too. I love uninformed monday morning quarterbacks.
A full-time company would probably handle that scenario by evaluating the market and seeing how to leverage their investment. For example, if your pop-up blocker had any intelligence to it, one approach might involve building the equivalent of adblock for IE, which I suspect would sell about as well as a popup blocker pre-builtin. Then again, I'm not sure how much of a company one could expect to build around a simple pop-up blocker, so calling yourself a company is a bit of a stretch -- it's really just a hobby.
No need to apologize for being a tool, this is the Internet and it is assumed.
Actually, scaling twitter is a solved problem. There is a company in India called SMS GupShup that does the same thing as twitter, except they have 3 times the number of users and more SMS users. And they don't have downtime.
SMS GupShup's business and technology are very different from Twitter's. SMS GS is geared towards distributing SMS's, not displaying them on pages/open API's. That makes a huge difference.
"It's not necessary to give your startup your complete attention to run it. I treated my shareware business as a part time job. Mind you, other companies that could focus attention on their competing products drove me out of business."
Did I get that right?