Do not coddle your tomatoes

I get my tomato seeds from Amishland Seeds. They are heartier tomatoes than any other I've tried.
Sadly, this year 80% of my tomatoes are stuck at the "second leaf" stage. The Pink Accordion is about 2 feet tall and has a thick healthy stem, the rest are not doing anything even though they get lots of hot sun, water, and wind.
For the next few weeks I'll keep a heating blanket on beneath them and light on all night over them. Their soil temperature was at 68 degrees and they've been getting 12 hours of sun before I added the blanket and light. Their soil is not too soggy.