In a game such as Overwatch, where every millisecond counts, having a teammate in the spawn can spell doom, especially if they're planning on switching to a new hero as well.
Instead of eating even more time while switching characters, this easy trick seems to not only allow players to make up for those lost seconds but even get back into the fray much faster than normal.
As shown by YouTuber McMagicMarv, if you are in the spawn room and are already planning to switch heroes anyway, there is likely no reason not to do this.
To get back to the action from spawn quicker, simply highlight the hero you plan on swapping to, burn your current hero's movement ability to get out of the spawn, and then switch to your intended hero. If needed, you can then even use your new hero's movement ability to cover even more ground.
McMagicMarv went on to demonstrate several heroes this works well with, from Doomfist and Widowmaker to Winston and D.Va. Additionally, they mentioned that Reinhardt, Winston, Echo, Genji, and Tracer in particular are other heroes players should try this out with.
Those on low mobility heroes during a high intensity objective situation could also change to a higher mobility hero while dead and then use this trick.
Of course, using this trick at all means sacrificing any ultimate charge your existing hero has as well, however.