Why the concept "data lake" emerged in the first place:

Thinking about what to store (and what to log) is not trivial and takes careful consideration. Plus, there's always the argument: "But what if we need something that we forgot to store or log?".

Answering that takes time and risk-acceptance that most developers in most projects don't get.

"Datalake" was just a pseudo-solution to gain peace-of-mind: We throw everything into a big bucket and figure it out later.