No problem.
Bark is the stuff on the outside of the plant material, everywhere but the leaves......
but seriously....
bark doesn't have the same resistance above ground, to the pathogens existing in the medium. If there is any damage, seen or unseen, it allows pathogens to enter into the plant much easier.
I also used to bury stretchy seedlings, until it became apparent that it causes issues.
Now, first option is to make sure such stretch doesn't happen, by applying sufficient light.
Second option is to stiffen them up with a fan and good light. Most plant will eventually become much bigger than the biggest seedling, so there is room to play with. You simply apply enough light to keep them in place.
If you bury the plant deeply in a pot, it must grow roots in an unnatural manner, filling the bottom and winding their way back to the surface, where chances are they will become entangled and "choke" the plant.
That is what I was thinking.