I really wish people who come up with 'radical' proposals like this actually did a little thought before sharing with the world at large. In this case, sitting down with a pencil and paper and defining exactly what they mean by "very beneficial".
The poster talks about being able to operate at 80 km/h, but seems unaware at what maximum speed trains currently operate (pretty close to 70 km/h).
So lets do the math the poster neglected to do.
We'll assume we are only going to deal with the large station spacings, most of which are pretty close to 2 km (ie Downsview to Wilson, Eglinton to Lawrence, Lawrence to York Mills, York Mills to Sheppard). Eglinton W to St Clair W is probably closer to 3km.
We'll assume that we'll take 0.5km to accelerate and 0.5km to slow down so we don't throw people around the cars. That leaves us with about 1km to operate at whatever maximum speed we're using.
I'll be generous and use 90 km/h instead of the proposed 80. That 1km will take 40 seconds to cover.
If we stick with 70 km/h, that will take about 51 seconds.
Over the whole YUS run, we are now looking at about 11 seconds * 5 big station spacings or less than 1 minute over the entire loop.
Want to try explaining the "very beneficial" concept again?