A single stock of Amazon costs just over $1500. That is more than the monthly rent a poor person pays. If they want Amazon in their portfolio, they can pick a mutual fund that includes it, and they wouldn't have to shell out anywhere near $1500.
As an aside, I find the argument that "this will help the poor" really disingenuous when you consider that the poor are the first ones blamed when things go awry. Remember 2008, when the crisis happened because "the poor were given houses they couldn't afford?"
Companies like Robinhood are not looking after the poor.
The solution to poor people not having enough money to invest is to get them more money.
If you are a very sophisticated investor (and I bet some people on this forum are) maybe that works. But in general people who trade stocks for themselves at home take a bath.
What? $5-$10 for a stock purchase? If you are purchasing such a small amount that the fee is > 0.1 % you should not be trading stocks. (In general you shouldn't.)