Because of the highly nested structure of HTML, it is possible to crash (from experience, with all the big names) your screenreader if there are a large number

Because of the highly nested structure of HTML, it is possible to crash (from experience, with all the big names) your screenreader if there are a large number of elements, especially if there are a large number of sub-trees, like you often find in technical documentation. HTML is accessible in theory... But in the real world, it can still be a terrible experience, unless the reader is highly optimised for streaming the HTML (not always possible), or the document is simple.