No, not redundant at all.
- A lot of people follow hashtags, you will only reach those people by using hashtags
- A lot of people don't want to opt into having their entire posts searched, which is why searches were hashtags-only in the first place, and they'll keep using hashtags
- Hashtags indicate intention to discuss specific topics, whereas non-tags could be accidental (for example post with #politics wants to discuss politics, someone who mentions it might not).