Quality post is not about size, length it could be long or short. Quality post is about useful information that is passed to users that come across it. How it can add value
Exactly! I’ve seen some short posts that are getting merited because of the value being given to the community. It doesn’t have to be long.
I tend to agree, as long as you contributed something related to the topic as a constructive one and can add further discussions. Remember that we're not making a blog upon posting, we're in the forum which is a big community that sharing ideas, thoughts, a chance to interact with others as long as you know about the topic or just you are expressing your own ideas freely and should be on the topic. So there could be no size at all but I don't know how could you express your idea in a short line or a single line.
In forum rules, there was an example of number 1 rules and this is clearly a no quality post.
Forum rules
1. No zero or low value, pointless or uninteresting posts or threads.
[1][e].
.
Examples:1. Such posts as "SELL SELL SELL", "I agree", "+1", "Support", "Watching", "Interesting", "LOL", "SCAM", "LEGIT", "FAKE", other one word posts, posts consisting mostly of swearing, quote pyramids, useless introduction threads, threads about a topic already recently discussed in several other threads.