Didn’t HTML5 remove the <center> tag? In that case, just seeing the HTML5 DOCTYPE should allow ignoring those elements (as in not styling them). For example, if I do:
<center>
Text
</center>
...just treat the tags as <doc> tags:
<div>
Text
</div>
I understand there are many websites following older standards, but I can wish (for HTML5 to have been “strict”)