...acknowledges "Said" is a fine word to effectively convey dialogue...Anyway, writing is a very subjective thing and almost every rule you can think of has a time and place where it works and doesn't work... Just like "don't use said."
Oh, fine. If you want the rant, you'll get the rant.
"Don't use said," phrased in that way, is inherently bad advise. "Said" is not only a fine word, but needlessly forcing yourself not to use it is not only an exercise in frustration and futility, but also incredibly obnoxious.
Ask yourself this: Why are you writing? If the answer is "To make art" then, yes, you should absolutely avoid 'said,' but you'd also need to do much more than that. You'd not only need an extensive grip of the language you are writing in with all its peculiarities and commons, but also fundamentally understand that which you will be writing will not be appreciated by an audience at large. You are actively trying to elevate the medium beyond the realm of normal consumption and would, thus, use extremely thought-out and uncommon words and sentence structures. That, or you go the complete other direction and boil it down to sound poems. Either way, you're going deliberately out of your way to avoid the mundane with purpose.
If it is literally anything else, don't purposefully try to avoid "Said."
While a big audience can definitely swallow some big words, the most appealing literature to the masses is also written in simple language. It is not about expanding the words you use, but about using the words you already know well. It's fine to strive to expand your vocabulary, but it need not be a goal. A lot of successful books have been written in very basic language that a lot of people can understand, and this is by design.
By telling a person they should avoid a word wholesale without explaining why, you're entirely missing the point. Even then, you shouldn't be telling them to avoid the word to begin with. The thing you should say isn't "Don't use said". What you should say is "Use said in these contexts" as that is not only far more useful advice, but also makes the fledgling writer think about the why and how of their writing.
And, to tie it into KISS, don't think too hard about your writing. "Don't think about it at all" is not what I'm saying here, though. I'm saying you should definitely give issues like these some though, but never get caught up in them. If you really struggle to effectively write without relying on some words, then just use those words. There aren't only a lot of options in how to phrase a sentence, but there's also a lot of ways to manipulate your own mannerisms into something readable and workable.
Source: I don't follow any of my own advice and my writing is fucking garbage because of it.