Transition words when used well reduce cognitive overload. However, when they are overused, they turn into unnecessary filler words.
Quoting from Yoast's article about why you should use transition words.
In this paragraph, I’m going to discuss a few reasons why practice is
important to mastering skills. Firstly, the only way to truly learn a
skill is by ...
I'm the kind of writer who advocates snapping on the gloves and doing the surgical method - that is, cutting out everything in your writing that is unnecessary and getting to the bone and tendons of the work. Adjective not needed? Cut it out. Passive verb taking up space? Kill it. Got a sentence that could work better with five words instead of ...