Satellite domains/websites have the function of guiding traffic to your main website.
But wouldn't it be better if visitors reached the main website directly? This is indeed the preferred solution, and you'll typically need the support of an SEO expert to achieve it.
Used intelligently however, satellite domains are a further way of attracting visitors to your main website. An example is where your main site has a name that is long or difficult to remember, and the satellite domain name is short and punchy.