No external links

TL;DR

Only premium agencies may have external links in descriptions of products, collections, etc.

External links and spam

Spam-bots crawl around the web looking for sites that allow posting and commenting in order to insert unrelated ad content on those sites. To some degree they wish to appeal to users of that site. But mainly they want to have links from those sites back to their own sites. Doing so creates false credibility for those target sites. The suggestion is that if many websites link to that target site then that site must be authoritative in the public's eye.

In the meantime you get a crappy site. Blocking external links from user content on this site helps discourage spammers from spoiling this website.

Local links are the exception. Links to other parts of this website are generally not considered spam. And they are nearly worthless for spam-bots crawling the web.

Premium agencies are allowed to

If you are paying for your agency to have premium features then you are allowed to include external links in your descriptions of the agency, your stores, your products, your collections, and so on.

How are links handled?

This question only comes about because products and other user content for design agencies have descriptions that contain Markdown text. That's essentially plain text but allows formatting of the sort you can see in the article you are currently reading.

We don't prevent you from adding links in your descriptions. And we are happy to allow local links to other content on this site. It's only external links to other websites that we filter. If your agency has premium status then your links are clickable and clearly visible as such. If not then they just look like plain text.

Google and most webcrawlers will not consider a URL displayed as plain text to be a hyperlink and will essentially ignore them. Thus discouraging spam-bots.