Whats the point in transplanting?

I'm growing in a small area so i was thinking about using 2 liter bottles or milk jugs

does anyone know how plants can get if grown in these?

also, would it be good to transplant into 2 liter bottles or just start the seeds in the bottles?

i would start them off in jiffy plugs or they rockwoll cubes or peat pockets which are simmilar to the jiffy plugs.......this gives the plant a better rootball...

dude i would use one plant per five gallons just to be for sure that they have plenty of room i used small stuff starting out before and you run in to root locks and your plants will starve each other out. But if you have order a dwarf seed i guess that might work good luck....i have my buckets in my journal

Transplanting gives your plants more space, thats the point. Your plants size will relatively correspond with the container its in. Ive seen an amazing grows in shotglass's with a 7 gram per plant yield. I grow huge monsters in 5 gallon buckets yielding 112+ grams per plant. If your space is limited, its best to grow in smaller pots so your plants ability to overgrow the space. Plants compete. Yields suffer.
Transplanting encourages growth spurts. Its much better when most the medium is a root ball rather than just space. I have to water my soil plants daily because of this. I check my roots to see when I need to transplant.