i always see people plating the seedling in a red solo cup or something in then transplanting it later to a bigger cup. couldnt you just plant the seedling in the size pot you want it to grow into?
if you plant a seed right into a large pot, you gotta be very careful not to overwater cuz without a big plant that takes forever to evaporate and in the meanwhile your seedling drowns... also in a regular pot the roots will mostly grow down and then spiral around the bottom, potting up from small pots can help with getting a more even distribution of roots in the end. there are air-pruning pots that basically dry off the root tips at all sides of the pot which promotes root branching, they supposedly work very well. with such a pot the risk of overwatering would also be reduced.
Yes you can, but it can be more challenging to get the watering right, as baumeister said. Not only overwatering but underwatering, the pot can still be heavy and filled with moisture in the lower half of the soil while your little sprout at the top could get all dried out.