No it's not. The same effect would be so if there were as many properties as there were people who wanted to live in them. Increasing BTL would still push up both property price AND rental price because of the above effect of substitute goods on supply and demand.
But Landlording has been insidiously worsening the issue. And it feeds itself: the more landlording there is, the higher the rewards for all landlords. And the bigger voting bloc they become. And the bigger the vested interests of our MP Landlords (near 20% of the HoC are landlords).
Which all ties in to the problem highlighted in this thread: is a government with a mandate only from the old going to serve the needs of the younger, poorer generations, or are they going to serve their older, wealthier voters?
The question is how long can this go on before things basically fall apart. The situation for the young is getting worse all the time. Private rental is increasing; home ownership is decreasing; the cost to the taxpayer of subsidising rents paid to private landlords is increasing. The young are thoroughly disillusioned and many do not want to be part of this crooked system, which exists solely to benefit the wealthy.
Many look at today's society and think, "There's no future for me here. I don't want to live all my life a slave in a job I hate and then die, because I won't even be able to retire the way things are going."
Our FPTP system ensures perpetual Tory rule, and we all know what their priorities are. Not those of the common man, that's for sure.
The whole game is rigged, and this country seemingly is yearning for a return to the Victorian era. All the while, economists warning of the perils of a growing wealth divide, and just about everyone talking about how unsustainable our current trajectory really is.
Going to be fun watching the whole thing unravel.