Your original point was that Doom was some huge watershed moment for gaming where PCs and the Internet gained prominence. I'm saying you're wrong.

1. Doom's distribution was (to consumers) largely CD-ROMs.

2. Doom didn't even support Internet multiplayer, only modem-modem or LAN (IPX/SPX).

3. The game industry was a multi billion dollar industry by the time of Doom's release. Doom didn't somehow accelerate growth of the industry.

4. Instead of being a shareware-only title like Doom, it's sequel was sold in big boxes like all other games.

5. Doom didn't influence people getting online (BBSes or Internet) as there was no sudden uptick in modem sales, account signups, or BBS growth associated with the game.

Doom was a fun game and got media attention for being popular and violent. It was not however some major inflection point in the game industry or Internet.