This is one of two posts that made things click for me. This one clearly distinguishes Functors, Applicatives, and Monads visually so that I don't get hung up on the names every time I encounter them.

The other article that demonstrated the practical purpose or path to constructing Monads showed a number of them using nested procedural syntax formatted to look like do-notation. [I can't remember the title/link, if anyone knows please post.] It went through async/await, maybe or list and showed them rearranged with the 'monad'ic parts off to the right where semi-colons might be.

Do-notation just took that and flattened the nested structures. The appreciation that these different computational contexts could all be structured the same way while focusing on what's happening apart from these contexts really demonstrated why it's useful and the power of being able to encapsulate these seemingly different ideas.

I'm sure I'll need to find a part-3 in my journey (perhaps Monad transformers) and so on, but I've at least got a good footing from those.