Is there any sense in using Postgres array of JSONB values instead of only JSONB?
Generally, if you have an array of one thing (statically typed), it's better to store them as jsonb[] (a native SQL array). There are far more functions that operate over a SQL arrays, and indexes. It also tends to less overhead in storage. JSONb only has,

jsonb_array_length(jsonb)
jsonb_array_elements(jsonb)
jsonb_array_elements_text(jsonb)


While Array has a far more, but most of those features are implemented as operators.

Ultimately, in most use cases it won't matter much. You're better off normalizing your data. You really shouldn't be storing multiple json documents in one row. That sounds like a big "con" to begin with.