I think it's more "the web" rather than "software", before the first dotcom boom the rule of thumb (for software and hardware companies) was that you had to have 5 profitable quarters before you went public (5, count them, 5!).

The original dotcom boom threw all that out the window, companies were going public on the smell of an oily rag and no product just because people wanted to buy a piece oif the web, we've forgotten what it takes to make a real company that lasts