The point is that regardless of where it came from parameterized queries are a staple of programming now, and having an example without it would be like having an example of a login system be
I'd much rather read a straightforward example like that in an intro, then reading the complicated prepared statement when going through what's essentially pseudocode.
There are valid cases where you're sure that the thing you're looking at is a valid id (ie. you already pulled it out of the database or by generating it yourself), not every program is a webapp that's handling user input, and examples like this aren't meant to teach you best security practices.
And yes the login system example would be acceptable if you're discussing something entirely unrelated to actually implementing one.
Template strings are the one ES2015 feature I still really haven't used much. And this almost seems like a textbook use case for them! I'll need to give this a shot in a toy project and see if I can't get my own version hacked together for support with my favorite database interface library in node (pg-promise)
>friends: dbQuery("select * from firends where user_id = "+userId).data