I, personally, am very grateful that my landlord has continued to own the home I am renting from her, rather than selling it.
I prefer not to buy a home right now, unless I have to, because I live in London and the stamp duty would be equivalent to 3-4 years worth of rent. Plus there would be the cost of financing the house. But I may not want to live her for much more than that. So renting is a much better deal for me than buying.
They have several properties, which means that they also have accumulated a good list of tradesmen who fix things effectively and quickly at a reasonable cost. Since most London houses are old, including the one I live in, things need to get fixed from time to time.
The fixable problem making access to housing so expensive is restrictive planning laws. If it were easier to build more houses, then the prices would end up going down.
The unfixable problem is that in every big city in the world, there are more jobs and opportunities, more people want to live there, and that drives prices up.
If we did not have portfolio landlords, only people who already have money could move to places like London, which would mean that the only young people who could move here and get onto the London job ladder would be young people who have enough money from their parents to buy. It is already difficult enough without adding that new difficulty.
So while some landlords are greedy and exploitative, taking inadequate care of their properties, some are fair and filling a very useful social purpose by providing housing to people who want to live somewhere that they cannot buy or do not wish to buy.