In almost all cases, there's a significant difference in the sort of risk that comes from B/FaaS dependencies and the sort of risk that comes from PL lock-in. The former leads to technology lock-in and vendor lock-in, while the latter almost never[1] leads to vendor lock-in.
Technology lock-in without vendor lock-in isn't that huge of a liability. A popular PL under an appropriate license isn't going to disappear tomorrow, and its creator doesn't have the power to hold your business at gunpoint. Conversely, B/FaaS providers upon which you truly depend definitely can extract (or by disappearing simply destroy) much more value than you originally anticipate.
[1] If you use Wolfram Language or Matlab then your choice of PL causes vendor lock-in, but most PLs aren't like this.
I agree - "vendor lock-in" seems like a valid point, although I don't know the details of many of these services. "Locked into a programming language" is something that will probably happen kind of naturally anyway.
Technology lock-in without vendor lock-in isn't that huge of a liability. A popular PL under an appropriate license isn't going to disappear tomorrow, and its creator doesn't have the power to hold your business at gunpoint. Conversely, B/FaaS providers upon which you truly depend definitely can extract (or by disappearing simply destroy) much more value than you originally anticipate.
[1] If you use Wolfram Language or Matlab then your choice of PL causes vendor lock-in, but most PLs aren't like this.