Wait, IdenTrust is the largest CA on the internet? This is surprising - I'm not saying he's wrong, but I'm shocked not to see Verisign, Thawte or Comodo in there at all...
IdenTrust crossigned the LetsEncrypt root. LE is def the number one player in this space today. Its not technically correct to sat IdenTrust is no#1 as LetsEncrypt is its own root. This article fails to mention LE at all.