I don't necessarily disagree with you, but provisioning 16-32gb for a production server doesn't seem to be unusual these days and the cost negligible...
<Insert electron/slack joke here>
<Insert electron/slack joke here>
For 100s to 1000s of servers. The cost starts mattering.
I'm not saying new applications shouldn't be built on lisp. Most applications don't have huge scaling requirements. But, if you expect the application to grow, have a plan in place for migration.
If you need 100s to 1000s of servers you presumably already have customers and money to spend.
Most of the time you aren't gonna need it (because you wont go far anyway as a company). And when you do -- like Twitter and Facebook did, you'll be swimming in users and money already anyway...