Obviously, the list doesn't make sense unless you know the products mentioned and their competitors, preferably with a bit the history over the last decade(s).

Obviously, the list doesn't make sense unless you know the products mentioned and their competitors, preferably with a bit the history over the last decade(s). The only thing all the products mentioned have in common is that they are free to use, as-in no upfront money. There are pools to hire for any software. First, the hype is cyclical, people who worked long enough will know multiple products. Second, new comers won't know anything so they will need to be trained anyway.