What you quote is not related at all to what Thunderbolt cables support beside Thunderbolt. It just states that you can use Thunderbolt to transmit DisplayPort signals. By that you're utilizing the Thunderbolt alternate mode to tunnel DisplayPort signals, instead of using the DisplayPort alternate mode [1]. Using Thunderbolt to transmit DisplayPort signals only works with devices which support Thunderbolt, not with screens supporting "just" DisplayPort. To make confusion even worse: All existing Thunderbolt controllers also support the DisplayPort alternate mode, so a lot of people who believe they're using Thunderbolt are probably just using the DisplayPort alternate mode instead. Afaik Thunderbolt cables usually support both, but I'm not sure if that's mandated somehow.
[1] https://en.wikipedia.org/wiki/USB-C#Alternate_Mode_partner_s...