Have you ever done groundwork (judo or bjj type groundwork)?
Being on your back is definitely not a great place to be if you have multiple attackers, but if you have a single attacker, it can be VERY difficult for them to stomp or kick you effectively.
I have minimal wrestling experience... I believe groundfighting skills are very valuable but nothing I've seen or read by self-defense experts makes me believe that being on the ground like that will go well. Maybe your experience is different
I'm thinking the attacker(s) are not barefoot and instead they are wearing boots or shoes with intention to harm. Blocking or avoiding a heavy boot or shoe while on pavement is a different exercise than fighting someone bare foot that just wants to sport fight on a nice, soft mat.