It wouldn’t bother me, but AMP complains about that tag in AMP pages therefore they don’t validate as valid AMP code and that’s bad for Google.
You can see it here by yourself:
https://validator.ampproject.org/
By entering this test code:
<!--
This is the minimum valid AMP HTML document. Type away
here and the AMP Validator will re-check your document on the fly.
-->
<!doctype html>
<html ?>
<head>
<meta charset="utf-8">
<link rel="canonical" href="self.html" />
<meta name="viewport" content="width=device-width,minimum-scale=1">
<style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
<script async src="https://cdn.ampproject.org/v0.js"></script>
</head>
<body>Hello, AMP world.</body>
<a href="https://example.org" alt="some alt text">hello</a>
</html>
More on AMP and Google:
https://support.google.com/webmasters/answer/6340290?hl=en
For example if a site has an article at this url:
https://site.com/article/
if the site supports AMP, it will deliver the AMP version of that article at the url:
https://site.com/article/amp/