Among the many questions I have for this site, some require me to specify the other person's MBTI type, like:
How should I bring up that subject with an INFP?
Are those questions on topic?
I think this is related to Are hypothetical questions welcome? Myers-Briggs is not universally accepted and is tricky to make general statements about. Some people find it useful, but you can't really say what a typical INFP is like beyond apparently being introverted, intuitive, feeling, and perceiving. You're not going to get good answers with your example question.
If you feel someone's MBTI is especially relevant to a question that represents a specific issue you yourself care about, then I think it's fine to say something like, "They're a typical XXXX; they try to see the good in things," if that specific quality is relevant to the question at hand.
Reading the other answers, I have some thoughts of my own.
As others have mentioned, MBTI is not universally accepted, and often I see attempts and arguments to discredit it. While I agree that including things like MBTI type in a question would likely not lead to discussions of Libras and Capricorns, as astrology has no research-backed validity, I have read many (seemingly-valid) points that maintain MBTI is not a particularly great predictor of actual behavior.
For example, as an INTP I typically value my alone-time, looking forward and projecting by intuition, thinking through my decisions, and acting via my perceptions rather than planning. However, I am subject to "personality swings" every now and then that do not align with my type; I tend to be quite extroverted with my friends, albeit my strong introversion most other times. Given this, one asking a question on how to approach me, "an INTP", may get answers far off the mark depending on our relationship.
Given this I would say that you should focus on the person's specific values and priorities (as far as you know), your relationship, and the context of the issue in order to get relevant and accurate answers. Injecting MBTI may complicate the issue by evoking potentially invalid stereotypes from the answerers.
Yes, and no
While I think it could certainly help, the majority of advice on how to deal with these type of people is often on the very sites where those personality types are identified and listed.
I think while you can include them, it will also be best to include your personal description of what they are like, so that those unfamiliar with that type of personality identification can at least access your question without having to research a potentially inaccurate personality type.
In addition it should only be used if it 100% suits the trait of that person, often they aren't perfect fits, meaning you can be providing us with inaccurate information.
At the end of they day they should be okay, but only as some additional information.