Most of it stems from the fact people confuse time gates with content gates. Even a few effort gates too.
A time gate is when time is the only factor the limits access to content. The Broken Shore "Campaign" was time gated with a new quest becoming available each week. A content gate is when you have to do specific pieces of content before more content opens up. Pathfinder is content gated for example. Effort gating is when a content needs to be done X amount of times (usually on a server level) before more content opens up. These are rare and I can only think of three instances being Gates of Ahn'Qiraj, Isle of Quel'Danas, and Isle of Thunder events.
Time gates are not necessarily a bad thing. They allow content to not be consumed instantly and leave a person with "nothing to do". And let's be honest here, the same people who complain about time/content/effort gates would be complaining that they had nothing to do because they blew through it all. They only become a problem when the content they are gating is boring and worthless like the aforementioned Broken Shore "Campaign" which had the absolute most stupid quests ever in it.
Amen to that. And the whole "They do it for subs" is stupid because that is not even a metric they use anymore. They use "Monthly Active Units" which means if you logged in for 5 seconds on the first of the month, you count as 1 MAU even if you never log in again until the next month.