SEO effects of footer attribution link to website builder’s site

I work for a web design business and we have been adding links in our clients’ website footers to our own as attribution (e.g.: “Website by Acme Co“, as plenty of other agencies do). What are the SEO disadvantages in doing this relating to the target website (i.e: our own website)? I’ve seen a few questions suggesting that in general, site-wide external footer links are not a good idea these days (e.g: Site-wide footer external link – is it a risk?).