b) Chris Sawyer had a team of graphic artists etc, IIRC
c) TT is not about a "train sim", but a business sim
Steam (which I'm guessing you're talking about) is nowhere close of being a monopoly. There are loads of alternatives out there, in wide use by people already. World of Warcraft, League of Legends, Minecraft, Roblox and more are all examples of big time successful games that never been available on Steam.
Of those options, the BBS one is probably the lowest cost, but -"shockingly"- that option is still available today... and is probably way easier for people to find your software than it was back in the day.
There are astroturfers out there who pretend that Steam is The Worst Thing Ever, but they distribute your game, dev-selected old (and pre-release) versions of your game, promotional materials for your game, and host forums and a news feed... forever. Valve also pretty clearly chooses to distribute games that are in the intersection of what's legal to distribute in the US and what the busybodies at MasterCard and Visa permit them to distribute.
If we lived in a just world, because of MasterCard's and Visa's enormous size, they'd be declared as something like "payment processors of last resort" and required to process transactions for anything that's legal to sell in the US, and subject to enormous fines if they so much as suggest to any merchant that MC/Visa will stop processing that merchant's payments for any reason other than a clear and obvious history of fraud.
Alas.
There are successful indie games that only entered Steam late in their lives.
Many games I own started their life distributed exclusively through a platform other than steam.
Arguably, you don't even want to approach steam distribution until you've already collected your hype. Steam no longer can surface gems, because it's just far too flooded, so you should seek alternative channels in general.
This hasn't been my experience. I've found that running the "Discovery Queue" a few times once or twice a week brings up an interesting game or two every month. It also brings up a bunch of stuff I'm not interested in, but that's the nature of game development... what you make isn't going to be particularly interesting to most folks.
There's also the "Show me a random game" link, which is fun to hit and see what crap it presents you. [0]