Earlier quoted context omitted.
Have you actually done an export of your Notion workspace? I looked at their options before using Notion and was happy they had a full export available - but then I actually went ahead and used it because they are putting zero focus into improving the performance of the apps - and the export format is a horrific mess! They split out code blocks from your notes in separate notes, the filenames are a mess and images ar…
Never used notion, but personally I'd prefer a machine readable and raw export, at least you can assemble your stuff back in any way you prefer. More annoying when you have to scrape data you're interested in from htmls. But yeah, lack of API is a major problem, and main reason I haven't even considered trying it yet.
Edit: I guess you meant human-readable as opposed to things like base64, and not as a critique against Markdown.
By now, there are several unofficial APIs at least, for read-access they are quite good apparently, did not yet use one myself though. E.g. https://github.com/kjk/notionapi