arguments against space as indentation:

• lack of accessibility
• lack of standardisation (i have seen, no joke, a codebase i worked on professionally with 3 spaces per level. and we were forced to maintain it)
• confusion when inputting depending on editor (if your tab key produces tabs not spaces, you have to press space several times per level to match rest of file)

arguments against tab as indentation:

• nhgguuuhh i don't know how to make tab smaller in my editor waaaah