Nesting rows and cols in Bootstrap 5 - theoretical question

A newbie here.Yesterday I started to work with Bootstrap 5 and I was trying some layouts.I structured one like this:

<div class="row"><div class="col-2">        not relevant content</div><div class="col-8"><div class="row text-start"><div class="col-12 col-md-6">                content 1 here</div><div class="col-12 col-md-6">                content 2 here</div></div></div><div class="col-2">        not relevant content</div></div>

Everything works perfectly, but then I read this on Bootstrap's docs: "Nested rows should include a set of columns that add up to 12 or fewer (it is not required that you use all 12 available columns)". I have two questions:

1. it's a matter of language barrier (eng is not my first language) or I understand correctly and what I've done is wrong - or at least not good practice?
2. if it's the the second case, why is that?

Thank you!