Before going independent, Instapaper was owned by Pinterest. To me it always looked like Instapaper was left as founders' sideproject so it makes sense that Pinterest potentially didn't want to invest much into it (build GDPR), or take risks (face GDPR fines). Now that it has been sold/given back to the team, I doubt we'll ever get to hear the full story.
I have major respect for Brian & co for continuing on the project and trying to make it a long term indie play.
I have major respect for Brian & co for continuing on the project and trying to make it a long term indie play.