It's not that hard to get deplatformed, but yes, I can see your point. From an operational ease of use perspective they are strictly better than PHP, at the expense of trusting the providers to do the right thing.

I believe at least one of the options you listed is actually built with PHP (Shopify).

Perhaps, but you don't have to know or care about that that to use it.

Same with WordPress. You install it (or have it installed) once, and then never think about what language it's written in.

Shopify is famously a Rails shop, but it is likely that a couple of the products on that list are built in PHP.

Shopify is Rails actually. I think Magento and Prestashop are PHP

Shopify is famously a Rails application no?

Yes