5 to 10 seconds is way too long for your team to devote when the enemy team still exists. It takes however long to pin him to kill him. Plus you get super good ult charge.

I've seen top players do it all the time on stream, and I've been doing it in mid master and from what I remember it's always worked out.

I could be wrong to an extent, maybe a Rein much better than I would say otherwise. Maybe there's nuance. Maybe depends on the rank too. I'm not an expert on game sense. But it's worked for me and I've seen it on top tank streams. You can base a scenario off ideals all you want, but if it works in game it works. There's probably something to it.