Is it alright or just frowned upon to answer from a similar systems perspective to give more options?
If the answer is applicable, yes. Answering a 4e question with something from Pathfinder often isn't applicable as the systems are not really related. Answering a Pathfinder thing with a 3.5 thing might be, but it's better to find the Pathfinder rule itself whenever possible.
The difficulty with this is that while there's similarities, there's also differences. You can trip someone up by giving an answer that seems entirely correct unless you have enough system knowledge to realize it's one of the things they changed.
Now, if the question is more about "how should a DM handle weird situation X?" or other things that aren't as rule based, your experience in similar systems is more relevant. Things like coming up with character backstory, interesting NPCs, plotlines, etc, all have universal issues across these systems and your experience applies.
Rule 0 of DMing seem to garner so much dislike from 4e or 3.5e
I suspect this is where your trouble really is. Rule 0 is a useful tool, but it's very easy to use it like a hammer and treat every problem as a nail. There are lots of situations where there is a better answer than to use Rule 0, and the community has been known to respond to people throwing rule 0 as the answer to problems that have another solution with downvotes.
If you were going to answer with rule 0, it'd be a good idea to provide some other alternatives first, and say "if none of those will work for you, then you can use rule 0." In my experience, that type of answer tends to garner a more positive response.
I try to avoid any questions that are looking directly for rules as written responses unless I can quantify it as...
This was from one of your comments. Rules As Written questions are explicitly looking for the literal written rule. If you're trying to quantify it as anything else, you're misunderstanding what is being asked. The best answers to a RAW question will quote specific rules or errata as evidence, and will not say something like "we houseruled this to solve the problem."
RAW questions are only interested in what the rules say.