Why are underscores not allowed?

I based it on SEO friendly url so the filenames also.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://studiohawk.com.au/blog/dash-or-underscore-in-url-heres-how-its-affecting-your-seo/%23:~:text%3DUnderscores%2520can%27t%2520be%2520used,underscore%2520character%2520isn%27t%2520permitted.%26text%3DGoogle%27s%2520web%2520crawlers%2520don%27t,your%2520file%2520names%2520for%2520you.&ved=2ahUKEwjZyKPZz-f7AhXH0mEKHZrMAKgQFnoECAoQBQ&usg=AOvVaw2ofAUI5VBr4saxvAJGF3HT

https://www.google.com/url?sa=t&source=web&rct=j&url=https://developers.google.com/search/docs/crawling-indexing/url-structure&ved=2ahUKEwjZyKPZz-f7AhXH0mEKHZrMAKgQFnoECAsQBQ&usg=AOvVaw2sW_PbujBh9BoHO7EEEMwH

But if the need is necessary I can make it available.

Fair point! Thank you for your answer.