Q: Is it really bad for on-the-page SEO to have a Title tag longer than 65-70 characters?
From the SEO point of view it is important to have your keywords in a Title tag. But remember that there should not be any keyword stuffing. The character number refers only to the number of words of the Title tag that visitors will see on their search results pages.
Your Title tag doesn’t have to be limited to 65-70 characters. However, it is better to make your Title tag short enough to make it visible on the search engine results pages for your visitors. Now it is often said that search engines limit the length of the Titles by the pixels, not by keywords.
So there are two main rules: