Meats don't really seal unless you're literally tarring them with char, and besides, juices leak from the side just fine. You really want to steam off the water content of a steak to get a better texture and fewer grease-runs. The entire meme about searing is literally just a decently crunchy texture. Flip steaks as much as you want.
The high "sear" temperature mostly implies a faster (and easy-to-follow) cook-time, but it still requires salting the steak to drain as much moisture as possible. It's certainly the smarter texhniwue, but not because it seals juices in.
(Also, "searing" a steak does in fact slow the rate of water loss, so it is easier to control cook-quality and easier to cook whilst distracted. But this undermines my main point that water content actually ruins the steak, and that you can get the same texture and taste with a different technique.)
First of all, I'm talking about searing on a flat top. Which doesn't char. And it does keep in the moisture. Especially if you've got fat on the side of the meat. But the best reason to do this is not to hold in the water, but to get a consistently even temperature in the final steak.
It is not a fast process. The steak needs to be rested at room temperature for an hour. Then seared 2 minutes each side, maximum heat, seasoning before you turn it down. Taken off the flat top or cast iron pan, which you deglaze, and pour over the steak. Rested another 30 minutes. Return to a cast iron pan and put in the oven at 450F for 8 minutes for a 1" steak rare, plus 2-3 minutes to medium rare. (11 minutes for a 1" ribeye to MR).
What happens is that the outside is seasoned brown, well cooked and most of the juice stays in, but the interior fat melts down and you end up cutting through a piece of meat that is exactly the same color and temperature from the inside to the very edge of the outside.
If you do want to cook on a grill, obviously don't grease-stain it by flipping it a lot or trying to sear it there. Put your cast iron pan on the grill, sear it in that, and then finish it on the grates for flavor and char.
I'm just pointing out you can get the same food with a quarter (at most) of the prep time and twice the flipping if you approach it experimentally at the same heat. Very much including basting. If you think steakhouses let steaks sit out before cooking them you're nuts—they might get nuked for five seconds for approximately the same effect. Letting them sit is just a convenience while prepping the rest of dinner.
Also, tenderizing the meat is about 10x as effective as letting it rest at room temperature. Not only does it warm the meat much faster, it reduces cook time, draws moisture out, and improves the crust. A minute of beating the shit out of the steak can trivially improve on an hour of sitting out (as if we have the time most days!). The grid-slice pattern is also very effective, even if it looks trashy. It's trashy because it's cheap and it works so well any cheap steakhouse will do it to obscure the shitty produce. Just make sure to do the tenderizing before you apply the salt.
Of course if you enjoy cooking, don't let my advice ruin it. Food is a lot more enjoyable if you feel satisfied eating it. Not everyone needs to optimize for cook-time.
The high "sear" temperature mostly implies a faster (and easy-to-follow) cook-time, but it still requires salting the steak to drain as much moisture as possible. It's certainly the smarter texhniwue, but not because it seals juices in.
(Also, "searing" a steak does in fact slow the rate of water loss, so it is easier to control cook-quality and easier to cook whilst distracted. But this undermines my main point that water content actually ruins the steak, and that you can get the same texture and taste with a different technique.)