Many of these guys developed their strokes before LD was a thing, and for some of the older guys, some of them before got set in their usual way before the much faster cloths were in common use.
And some of it is because they naturally feel out shots using pivot english, and bridge however long is near the natural pivot point of their cue. As far as taking the first warmup stroke with the tip near the bottom of the ball, that's a little bit rarer. Players who do say it helps them see the center of the ball and line of the shot a little better. I don't recommend it unless you have an unnatural ability to subconsciously feel out a shot while shooting fairly free-form.
Commonly encountered problems with a long bridge: Less control over soft shots, precise impact point can go a little weird on you, it doesn't work with some more highly technical stances (if you're tall and like to get your back low to the table, reaching forward and shortening your bridge helps stabilize you while a long bridge keeps you hand nearer your body can can require you to hunch over a little and/or sacrifice some stability) and of course when you suddenly need to play a shot off the rail, you're forced to shorten your bridge up anyway.
M.G. said:
I'm also strongly convinced that most pool players cannot serve as a good example.
You need to find a player that is working and not feeling, such as Hohmann, Feijen, Souquet.
Listen to this advice. Those guys are excellent examples of a very technically sound stroke. David Alcaide is another good one. SVB and Shaw are monsters, sure, but they get away with funky habits and (imo) poor stance because they have the natural talent to such an extent it doesn't matter.
If you're using that funky pro taper, then you have a problem because it doesn't slide consistently as a canonical taper does, so you need to again find the sweet point.
Well, many pool players will need to use a closed bridge in some scenarios, particularly big draw shots and avoiding fouling another ball with your stick when you have to really let your stroke out. A closed bridge can get funky with a concical taper if you're using the longer backswing that most pool players have. (Though I prefer a short stroke myself) Generally most pro tapers ARE long enough that they can slide comfortably through even a Filipino bridge even with a long bridge length, and if you have to bridge long enough that you're running out of pro taper, you're probably stretching for a shot where you're going to be forced to open bridge and not full-stroke it anyway.
Van Boening has a horrible stroke. Please watch more Snooker and play with Carom guys. It will open the world to you.
Yes, definitely watch snooker. Hendry, Higgins... from blackball and chinese 8 ball watch Gareth Potts. Unfortunately some of the monsters in snooker too, because they played the game from the time they could see over the rail, have some less than picture perfect habits, just like in pool. Ronnie O'Sullivan often has the back of his cue higher than you would teach. But still much better to copy than free-form players like SVB, Alcano, Bustie...