[...] but nowhere mentioned that other "tricks" are also needed to get it working.
Simplifying a lot: SMTP, as its name implies, is a very simple protocol created in the days when the internet was all fun and giggles. In consequence, it was also not quite secure enough so email providers have been implementing other measures (OAuth, etc.) to make at least the login to their servers secure before you can even start an SMTP conversation and from there come the "tricks" you talk about. They are really login "tricks", not SMTP tricks.
And what about to use not use Gmail as SMTP, but my internet provider's SMTP?
That, of course, depends on the provider and the security measures they have implemented, if any. Although nowadays most of them require some kind of secure login for which you'll have to use some "trick" or other