Multiline comments are a bit of an anti-pattern at the best of times.
If you're making this as a general statement, it varies from language to language. For example, CSS (and arguably HTML and Markdown) only supports multiline comments, and multiline comments are often used for documentation (as with jsdoc and, though only comments in the same way that heredocs to /dev/null are, Python).
But yeah, if you actually do this in Bash, wat.