Regardless, the problem is that autists are not able to read others well and gauge whether they are indeed interested in what they're saying (especially since it's polite for the other party to feign interest), nor do they realize that others may not be as excited about a very specialized topic they took a liking to.
For example, most people will say they like coffee. For some it means they like to experiment with different grind sizes and flow rates to extract the most floral notes out of certain Arabica cultivars when brewing espresso, but for many it will mean they enjoy the lifestyle of going to Starbucks and ordering a Latte with sweeteners, and have no knowledge nor even any interest in what coffee is and how it is cultivated, harvested, roasted or brewed. Autists would immediately assume the former and fail to pick up on the fact they're facing the later scenario.