The AGPL requires you to provide a link? That would be weird. AFAIK, the GPL does not demand that. It suffices to send the source code on demand. Besides that, what would happen if your link would stop working?
Where I work, we use a lot of free software to build our product (various licenses) and I am happy to hand over the sources of these libraries to anyone asking. So far, no one has asked, though.
> If you commercially distribute binaries not accompanied with source code, the GPL says you must provide a written offer to distribute the source code later.
So if you don’t send the source along with the binaries then you need to make a written offer to your users. However, [2] states that:
> If you make object code available on a network server, you have to provide the Corresponding Source on a network server as well.
So you can’t publish the binaries online but only distribute the source via physical media, for example.
It requires you to prominently state the license choice and some consequences thereof, and if you don't provide a link or a physical copy of the source then you must proactively provide a notification that the source is available (there are constraints on that notification, but I don't remember them off the top of my head).
It definitely does not suffice to simply send the source code on demand without additional up-front work.
To be precise, the AGPL requires that, if such a link is present, you may not remove it. And yes, this is precisely why AGPL exists and GPL is not always sufficient.
Where I work, we use a lot of free software to build our product (various licenses) and I am happy to hand over the sources of these libraries to anyone asking. So far, no one has asked, though.