Structured content deals with the structure and use of a site, while the semantic elements deal with how these component interact with themselves and the user.
Structured and semantic elements serve algorithms and users when working together, and make a complete experience that works properly for people and the technology they utilize.
Having both enables your website to be legible to both people and machines.
I appreciate the recommendation to self reflect and identify why you're holding yourself to an unhealthy standard, I have problems with perfectionism, and identifying why I won't leave projects alone could be helpful in producing more work.
Hyperbolic discounting is the tendency to become more rational the longer you have to wait, and a recommended method to counteract it is to assume that the future you cannot be trusted, and to trust the present more.