What does the phrase 'by lack of' in this context refer to?

Question

Is the "by lack of" here grammatically correct? Here is the whole context, with emphasis added.

6. Function fields

I will only say a very few words about the "geometric" analogue (or "function field case") of the various theories described before, mostly by lack of proper competence. More detailed explanations will come in future chapters.

Answer 1

for lack of appears to be the more idiomatic construction.

Anyway

“By lack of” ,conveys the same meaning.