I'd say that is misleading at best. Lambdas are inherently unsuited for monoliths due to payload, RAM and execution time limits and cold start times. Lambdas are inherently suited to "real" micro-services, because by nature can only do 1 thing and have strict limits.

Depends entirely on workload - there's 3GB RAM available, which is more than what we use for normal monoliths on Heroku. Payload limits are 6MB or something, which isn't hit for a majority of sites on the internet (each request, not total page size). And there's nothing in the nature of Lambdas that force them to do only one thing. HTTP events can be fed through the normal router (lots of adapters for many web frameworks out there). Non-HTTP events can either go through a switch-case-board. There's no inherent "nature" to lambda, it'll execute whatever code you give it. There are limitations, but those are constantly changing.