I was wondering about this myself.

Last summer after a lot wet weather, my tomatillos formed roots on the lower stems, and some branches that had bent down to the ground had roots forming where they touched, especially at leaf nodes.

If no one has an answer, I may just try it, since I have a couple of leggy tomatillo seedlings.

I had mine planted both ways, last season I planted them deeper because they were leggy and this season I planted them at the same level of the soil. It seems to me that the ones that I planted deeper fruited later than the ones I have planted at the same level. I also have some that are volunteers and they are fruiting already at a much smaller size than the ones planted. I would say you can do either way.

Silvia

I had some that got large and fell over and formed roots all along the stem. After that I started planting them deeper and they still do okay. The most problem I have with tomatillos is that they attract some type of beetle like magnet lol.
~SJN