Every researchers in the world have their own webpage.
Publication list on the web page is and advertisement of the researchers' ability. Portfolio. The researchers' webpage is important for their career path.
Other researchers may read the paper on the website, and may cite the paper. Putting papers on the webpage is important to increase h-index.
Introducing the research work contributes to science development, industry growth, and education. Providing your knowledge is a kind of a noblesse oblige.
Researchers' webpage is useful to find the adequate person to involve in society's work. It is also useful to find lecturer or presenter, and it is useful to explain in the organization why he/she is adequate for lecturer/presenter.
Some country have a culture that the person without hobby is not attractive. Therefore, researchers often write their hobby on their webpage.