I fully understand what you're saying and agree that on an individual level our impact is minimal compared to these companies, but I always wonder how fair it is to say they have to change and that's the only solution.
My understand, and this is of the top of my head, is that 93 of those companies are oil/gas companies and the other 7 are cement. If they all gained a conscience today and stopped operations tonight, the world would be in chaos. People on an individual level would still need fuel to be able to get to supermarkets, and the supermarkets need fuel to get food moved around the supply chain.
Whilst I'm not saying it's a solution and I'm using a simplified example to make my case, but if everyone prioritised buying electric cars as their next car, then manufacturers would speed up production of them and phase out combustion engine cars and vehicles. This would reduce the need for oil and at some point these top 100 polluters would either adapt or collapse.
What I'm trying to get at is the masses need to put pressure on these companies both through policy changes and purchasing power. I think it's too easy to keep driving petrol cars and pointing at the oil companies as the bad guys.
Just responding to your edit, I think it's a great thing that you did start this wider conversation. I find it refreshing that on Lemmy people are having much more detailed conversations and raising these wider talking points. Back on the old place a lot of people would just try to drop short gotcha type replies that were repeated over and over just to get karma, it got boring.
The only thing I will say is I think you failed at not derailing the conversation slightly!