Chozo Ghost, I have to agree that Sega should only be angry at themselves and Sony over having to quit hardware. With Nintendo, there was rivalry because Sega created it themselves, running an advertising campaign to try to tell customers to take one or the other, and that the Genesis was the right choice in the market. For quite a long time, Nintendo did nothing in retaliation, and eventual had a similar campaign, but for the most part, the Sega/Nintendo rivalry was advertisement and fan-based only, IMO. Sure the companies didn't like each other as competitors, but neither company used underhanded tactics against each other at all.
With Sega and Sony, this doesn't hold true. The Saturn completely lost its era from its own lack of virtue, but the same does not hold true for the Dreamcast. From before day 1 of the DC, Sony was talking big and bad about the PS2, telling consumers in interviews and specs, telling consumers and publications that the PS2 could control smart missiles, could create a Toy Story level of in-game graphics, and that generally the DreamCast was a waste of time and money, which, in truth, was not true. As a result, people just didn't pay much attention to the DS, especially in the states, and things fell apart for Sega because of distinct Sony lies in this generation.
I have to peg these statements and platform chances to the "Publishers are idiots" category. It seems to gather more and more supporting evidence everyday.