Each of us is an individual, to be recognized by our accomplishments; more recently, to be addressed in a preferred manner. It's a form of respect to refer to a person.
If everything was asked and answered by anonymous instead of real and pen names there would be greater encouragement to ask and less incentive to answer. Vote up requires 15 reputation and vote down 100, also there are badges which encourage up votes. Voting is skewed towards up, a system of recognition for good questions and answers.
It is true that some have high reputation on one site, or multiple sites; and to see that one must click through to the user's Profile. It is also true that some have extremely low reputation, literally joined yesterday. Experienced users know that neither makes them correct or incorrect, indeed it is the quality of the post.
I have seen many instances where someone with a Doctorate didn't read the help file, and understand the standards for asking or answering. By recognizing the name, and knowing that they were new, it enabled me to comment; direct them towards the help file and assure others of the community that useful interaction would be forthcoming - indeed there was as they gained 1000's of reputation in weeks.
Where there's a tie-break needed, (for you the asker, or a 3rd party reader) it can be useful to see that one person has been vetted over others; you can take a chance with trying the lower reputation answer over an accepted answer provided by a high reputation user, or vice-versa.
Otherwise one ought to upvote and accept that which is correct - practicality things work differently. Somethings aren't as cut and dry as a polariton, as separable as a lamilar flow, or as complicated as colliding vortex rings. While some people do score upvotes for subject, humor, good looks, or reputation it's the reputation (and badges) where each can improve and claim knowledge on more than a single point.
Locking a vote prevents retraction, when it is discovered that there was a voting error. Not knowing whom supplied the answer leads to more head scratching and triple checking, potentially by someone whom doesn't understand the subject, than simply crediting the author; and potential problems that may cause.
Arguably the reputation of other answerers might assist to determine that one high reputation answerer got it right, or wrong. A mix of anonymous questions and answers surely is not better than ones attributed to an account that someone has worked hard, often for many years, to establish.