It doesn't promote it, if you ask me, because you gain nothing. It just allows you to do it, like the game allows me to be in A1, even though the current flag is in H10.
We could also talk about creating a tunnel area that goes flag to flag, similar to TC, but in R/AAS, making all areas outside of it out of bounds. Current game design allows for clueless people to roam around the map instead of playing the objectives... but it also allows smart people to roam around the map and do great things.
If both teams play equally (fantasy example), and one team returns logi to main, and the player gives up and respawns, but the other teams logi driver doesn't do that, and in the end they win 1-0... maybe that guy shouldn't give up. That's the magic of such games. After all, "there is no right way to play Squad" is something thrown around often, but it goes both ways.
Also also, imagine the team got pushed back to last cap, a sneaky logi goes behind enemy lines, deploys a hab, and since the whole team is close to main, then can easily just drive back and respawn behind enemy lines magically (with full ammo, because they were at main to rearm, further exploiting this design) and cap the enemy flag back. Nothing inherently wrong with this as far as game design goes, but Squad tries to be somewhat realistic and this bypasses some pretty large desires of the game - progression, overcoming odds through teamwork, skill, movement, manoeuvres, coordination etc., so it doesn't fit in the vision.