I certainly see your point & agree with overall gist of your post. Iím not disputing that usually traffic is indication of healthy site either .
Iím merely contesting that traffic can not be taken as a leading sign of quality of link Ė at least not yet.
Generally agree with point #1 & 2 mentioned in your post. Personally have a site of the type you mentioned in your point #3 ( not seo'ed at all, 200K social media views /pm )
Disagree with your point #4
Iím aware that WWW TOS do not allow external sites, but I hope Iíll be allowed to reference couple of not for profit international association sites to prove my point:
a ) hbscDOTorg/contactlinks.html ( Health Behaviour in School-aged Children Org )
Compete traffic uniques ZERO! , TBPR 6, MT 5.73, DMT 5.78, MR 4.49, PA 34
b) ibfanDOTorg/useful-links.html ( International Baby Food Action Network Org )
Compete traffic uniques = just 421, Site TBPR5, page TBPR 0, Page MR 5.33, page MT 5.89, DMT 5.64
Look at the co-citation of above pages. Linking out to WHO, NHS, TheLancet, Unicef, etc , etc
Do you really think getting a link on those pages would not help just because the domains have ZERO traffic or <500 uniques?
I feel they would be excellent pages to get links from despite their abysmal traffic.
On the other hand of spectrum, we have lot of sites run by the list building , direct marketing guys syndicate who have long page sales letter type 1 page sites attracting 40-50K traffic .
Doesnít mean search engines love them or they are of high quality? I donít.
P.S: Most of what I know about SEO / Link building is thanks to You & other excellent members at WebmasterWorld, SEL & itís fun to disagree with someone Iíve learned so much from :)