Links from which type of sites will effect the SERP's!!

[mediadrug]

You have also given the answer to your query. I agree with you partially not fully. Not all site give dofollow links but some give. See this blog  - https://ezinestack.com/mobile-phone-buyi...edit-card/
And https://deals.megamobiledeals.com/ has published their guest blog here and it is dofollow link. 
We have seen the varieties for dofollow and nofollow links from tried party sites. There are several forums also who provide nofollow link with some provides do-follow links. But all time we should not focus on dofollow or nofollow. We must consider the traffic of that third party sites.

Even if you get a link from BBC. Still it won't matter in your rankings if its a no-follow.