That's part of new user restrictions which for some reason is not documented.

User with up to 10 reputation, including 10 rep will have the link as plain text. Example.
User with 11 or more reputation will have the link clickable. Example.

The network profile doesn't have reputation of its own.

I think you are correct though, I suggest that unless the user has at least one account with more than 10 reputation, the link will be plain text.

Update: As of November 2017, all Website fields and links in the "About Me" profile sections are unlinked on stackexchange.com, for all users regardless of their reputation on any site. Hence, the below answer is obsolete and the feature request here is obsolete as well.

That's part of new user restrictions which for some reason is not documented.

User with less than 10 reputation will have the link as plain text. Example.
User with 10 or more reputation will have the link clickable. Example.

The network profile doesn't have reputation of its own.

I think you are correct though, I suggest that unless the user has at least one account with more than 10 reputation, the link will be plain text.

That's part of new user restrictions which for some reason is not documented.

User with up to 10 reputation, including 10 rep will have the link as plain text. Example.
User with 11 or more reputation will have the link clickable. Example.

The network profile doesn't have reputation of its own.

I think you are correct though, I suggest that unless the user has at least one account with more than 10 reputation, the link will be plain text.

That's part of new user restrictions which for some reason is not documented.

User with up to 10 reputation, including 10 rep will have the link as plain text. Example.
User with 11 or more reputation will have the link clickable. Example.

The network profile doesn't have reputation of its own.

I think you are correct though, I suggest that unless the user has at least one account with more than 10 reputation, the link will be plain text.