You are conflicting trivial with bad. In the specific case you complained about, I agree that it's useless. The original proposal of template aliases was not to introduce a redundant feature for typedef.

In general however, the other stuff you mentioned isn't useless. People make the same mistakes over and over or ignore advice, thinking it's unimportant. Downvoting answers which offer this advice is nothing but harmful. The fact that answerers have to constantly provide this advice (some question askers ignore previous advice and post questions with the same mistakes constantly) is not the fault of the answerers.

using namespace std; is not a big deal in trivial code. It is a big deal when they start to create multi-file programs, use third party libraries, or anything remotely non-trivial.

Readability and formatting is easy to comment on. That doesn't make it less important. A lot of time could be saved if people would just plop their code into an IDE, and press CTRL+ALT+F, or an online beautifier. But it's a fact of life that people don't. The laziness extends to other aspects of code: poor choice of variable names, horrible program structure, not using tools (i.e, the standard library) effectively, and so on. Since these things aren't taught in schools, it's not a surprise that it's a skill that's highly valued on this site.

Also, you can't expect everybody to be at the same level of skill you are. If commenting on "minor" things was disallowed, it would be impossible for lower rep users to gain rep at all.

Finally, and least important, this is from the help center:

Use your downvotes whenever you encounter an egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect.

The only point I can kind of see applying here is "no-effort-expended post", but as experienced programmers know, repeating general advice which falls on deaf ears is not low-effort, it's actually quite exasperating.

You are conflating trivial with bad. In the specific case you complained about, I agree that it's useless. The original proposal of template aliases was not to introduce a redundant feature for typedef.

In general however, the other stuff you mentioned isn't useless. People make the same mistakes over and over or ignore advice, thinking it's unimportant. Downvoting answers which offer this advice is nothing but harmful. The fact that answerers have to constantly provide this advice (some question askers ignore previous advice and post questions with the same mistakes constantly) is not the fault of the answerers.

using namespace std; is not a big deal in trivial code. It is a big deal when they start to create multi-file programs, use third party libraries, or anything remotely non-trivial.

Readability and formatting is easy to comment on. That doesn't make it less important. A lot of time could be saved if people would just plop their code into an IDE, and press CTRL+ALT+F, or an online beautifier. But it's a fact of life that people don't. The laziness extends to other aspects of code: poor choice of variable names, horrible program structure, not using tools (i.e, the standard library) effectively, and so on. Since these things aren't taught in schools, it's not a surprise that it's a skill that's highly valued on this site.

Also, you can't expect everybody to be at the same level of skill you are. If commenting on "minor" things was disallowed, it would be impossible for lower rep users to gain rep at all.

Finally, and least important, this is from the help center:

Use your downvotes whenever you encounter an egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect.

The only point I can kind of see applying here is "no-effort-expended post", but as experienced programmers know, repeating general advice which falls on deaf ears is not low-effort, it's actually quite exasperating.