During 2018 there was a collaborative blog called the Data Marks.
Mark B
Location: Cleveland, OH
Tableau Public Portfolio: https://public.tableau.com/profile/mark.bradbourne#!/
Certifications: Tableau Desktop (v10) Qualified Associate, Certified Business Intelligence Professional (Business Analytics)
Mark K
Location: Dublin, IRL
Tableau Public Portfolio: https://public.tableau.com/profile/mark.kernke#!/
Certifications: Tableau Desktop Fundamentals (v6.1)
Mark J
Location: Grand Rapids MI
Tableau Public Portfolio: https://public.tableau.com/profile/mjurries2#!/
Certifications: Tableau Desktop (v9)
Blog Posts
Common Oversights in Data Visualization
Improving your Data Storytelling
Control Charts in Tableau, Or How I Learned to Quit Worrying and Love XmR