I think you would find that while many writers of articles place great focus on tempo -- there is no difficulty in finding articles placing great emphasis on this -- you would find it a far, far tougher task to find an experienced and successful bodybuilder or strength athlete who places remotely similar focus on it.
You might be searching for years.
Yes, it is good to keep in mind and keep track of the fact that say 8 reps done fairly rapidly in a style typical of most bb'ers and strength athletes is a different task than 8 reps done with with say 2 second positives and 2 second negatives, and a different task still than when done with say 2 second positives and 4 second negatives.
And if doing something really unusual like 5 or 10 second positives, that's still a different task yet.
So if doing an non-typical-for-you tempo, if you record your lifts it's worth noting the different tempo.
However, that is not to say that limiting yourself or placing great emphasis on these less-usual tempos is necessarily going to help you much, if at all.
Oddly enough, what with all the thousands (probably) of articles written with great emphasis on tempo and on speed of negatives, I've yet to see one that makes the absolutely key and highly relevant point that speed of negatives is strongly and absolutely correlated with both:
A) The amount of positive work that can be done both in the set and in the total workout, and
B) The total volume that the body is able to tolerate.
Both go down, quite significantly.
There's a price to be paid for unusually slow negatives. It's not all benefit.
Lastly, sadly enough some authors can't use words accurately and their stated tempos are pure bullshit, e.g., using phrases such as "(such-and-such) true seconds" when videos show that their method in fact is twice as fast as that.
Unless you've seen a video of the author training someone using a tempo that he states, you cannot be sure that the "seconds" are real even if he uses a phrase such as "true seconds" or "real seconds." Sad but true.
Lastly, another tempo related thing that I don't think that I've read is the useful technique that I call "milking it."
Say that your training cycle calls for doing so many reps in this set, let's say it's the last set for the given exercise, and working at your normal tempo you are able to discern about say 2/3 of the way through that you will definitely make it relatively easily, but not so much so that going for another rep beyond the plan will necessarily succeed, or perhaps your method is such that you do not do additional reps beyond the plan.
In this case, you can "milk it" by making the tempo a little more difficult. Not so much so as to have any chance of failing the last planned rep, but enough to make the last rep of typical difficulty for the last rep rather than let the set be easier than typical.
Even if you don't have reps planned out, there are situations where you can see maybe one or two reps from the end that the weight is, unintentionally, an "inbetween" one -- a weight that is a little lighter than necessary for say 8 reps but too heavy for 9 (or whatever the numbers may be.) So even without a definite target number beforehand, you can see that if you don't "milk it" you will either have a relatlvely easy last rep, or will probably bomb an additional attempted rep past that. So instead you can slow the tempo just enough to make the set nice and difficult.