It's your soil ph that matters in a soil grow. Water ph matters,but not a lot if it is soft water.
There are great reasons to transplant, just not when the seed is just popped. You can start in seedling soil, go to 50/50, then to full strength soil, a gentle transition. Each and every transplant you can inoculate very effectively with myco fungi, a great benefit in organics. You save energy in early veg by running smaller lights. You don't leach nutes out of your soil as much before roots can get to them, and each transplant of fresh dirt is all the food they need for several weeks. Easy as fuck to get through veg on this routine. In short, those opposed to transplanting are big scaredy cats. Grow a pair!