Can confirm. The dot-com era startups I was involved with all had Oracle DB on Sun hardware. Apache was common. Java was somewhat common if you could deal with its slowness. C++ was common if you could deal with memory problems or needed more speed / efficiency than Java.

The VCs I talked to said it was a business decision. They had money to invest, so startups could afford to buy soft & hard-ware that had gone through a QA cycle or two. The VCs figured the exit strategy for most of their startups would be via acquisition, possibly by another startup so they wanted to have a standard environment to make integrating companies tech stacks easier. Or at least less distracting.

I have this vague memory of Yahoo! execs complaining about Viaweb / Yahoo! Store being written in Lisp and management freaking out that they couldn't hire enough Lisp people fast enough. Or at least that's the story that was going around the valley. (Isn't Paul Graham around here somewhere? Or someone who could point to a canonical reference where he talks about Viaweb getting acquired by Yahoo!?)