That’s really not very re-assuring. While we’re ultimately concerned with user experience (site must load quickly) there is another impact of these multiple DNS lookups and why we test with tools like Google PageSpeed Insights and GT Metrix: Site speed impacts our Search Engine Ranking.
So, while it could be true the end user may not experience any noticable visual delay, search companies factor page load time in their ranking. All those extra DNS lookups are significant and adversely affecting your customers’ search engine ranking.
There’s still no explanation why you must have all your assets distributed accross so many domains. Your explanation is more of a dismissal than an answer. Good try though.