I disagree as far as cannabis is concerned, and I'll repeat what I said in an earlier post. I've transplanted more autos than most people on this forum. I took the time to observe and adapt a technique that optimizes the success of the transplant. The key I believe lies in a couple of steps. Transplant as soon as the leaves are as wide as the pot. Don't transplant when the soil is dry, water moderately first and give it a few minutes to be absorbed. I take one of the pots I start in, fill it and use it as a mold to create an exact hole for the seedling in the larger pot by filling in around it.
Work directly over the larger pot when you transplant, keep the distance from the seedling to the hole to a minimum.. Remove the pot from the root mass, not the root mass from the pot, it helps prevent the soil from breaking. tip the root mass into the hole and compress the soil around the root mass. EVERY time I've done this, I can measure growth within 8-12 hours. there is no root shock, there is no stalling.
The other advantage of transplanting is I can start the next grow so that there is no downtime in between. My seedlings usually get transplanted within a day or two of harvesting the current grow.
No, transplanting doesn't work for all species, but we're talking about Cannabis. It works and it works well when done right and with care.