The practicality of knots and their traits is what drives their use. When you deal with boats, you need these knots to perform and not come undone when you are not expecting them to (which could be dangerous). And you also need them come apart when you need them to.
Properties like that are what makes a lot of these knots so useful. Technically, you can get by with knowing only a handful. But there are a lot of specialized one with niche usages.
There is a very nice animation on the site for the Monkey's Fist (where I just now learned the finishing touch to deal with the loose end of the line).