There are many different perspectives to look at the musers whose questions or answers dont get upvoted.
In the initial days immediately after musing got delegation, it was comparatively easier for the musers to get upvoted as the size of the vote was big enough and the musers were limited.
But as the popularity grew up, many more musers joined the platform and obviously vote got divided between more users, as a result the vote value reduced and number of users increased.
One should please note here that steem blockchain has imposed certain restrictions on the upvotes.
Additionally, musing moderators curate the content manually, which adds to additional restrictions due to human capabilities, there are restrictions in terms of number of times and value. As more and more people would use this platform, it will not be possible to keep everyone happy.
So please keep posting good and quality answers without expecting upvote everytime.