Very cool, if true

They only run the trams on the 5-minute schedule during rush hour. At that point there's often a tram on Princes Street trying to get out to the West End stop wedged behind a row of busses, a tram stuck at St. Andrews Square behind it, one at York Place terminus holding up the one coming in FROM St. Andrews Square leaving a tram stuck on the other side of the Princes Street stop and... I've been on trams out as far out as Murrayfield which couldn't move on to Haymarket because of the tram in Princes Street trying to get out to the West End. All the stops were full.

There's a limit to how many trams can run through the city centre when it's busy, push more trams in there and they just stack up and grind to a halt.

As for the idea of expanding housing etc. in the Edinburgh Park and Gyle area area, dealing with commuting from there is easy, just run more bus services. They can even serve commuters who don't live right next to the tram line.