Is accepting guest posts from backlink brokers like The Hoth or Authority Builders worth it?

I've noticed most of the larger backlink brokers also have an option to join their list of publisher sites. That way when one of their clients requests a guest post or niche update the broker sends you a pre-written article article with a request to publish.

Does anyone have experience with these submissions? Are there any major downsides? Does it actually help increase traffic in the long term?

I'm currently outsourcing content so any free SEO optimized articles (even if they require heavy edits) are a win in my book.