When OP finds on his own the answer or a workaround to his question, it is beneficial to the community to know the answer. Also, it shows “frequent contributors” (what about a club membership card and reward programme ?) that OP has taken the pain to investigate, search and study. OP has not waited passively for a pre-cooked solution.
There are also questions turned into tutorials by experts: a question, thought to be representative of a widely shared problem, is asked with the answer immediately written to serve as a step-by-step guide. Usually, such “tutorials” are rather related to AskLO site, see the Guidelines for asking as an example.
The problem is rather the poor ergonomy of the AskBot framework. It seems there is no way to have a “permanent section” where the rules could be better explained than in the present situation. This permanent section could also hold several recurring questions with comprehensive and definitive answers.
The biggest difficulty with newcomers (I remember how I was scowled in the beginning) is to understand the difference between a Q&A (question and answers) site and a forum. A forum is a sequential chronological conversation which progressively converges toward success or failure. In Q&A, the question is unique but editable to be accurate, precise, detailed and informative. Each contributor is then allowed a single answer which is also editable for improvement.
Comments are there to request additional details and, theoretically, should be considered as temporary and expendable: their important information should be transferred either in the question or the answer.
As for your question: yes, OP should be allowed to answer his own question but he must be made aware of the rules. This is the real issue.