blacklash against GPL viral clause
I think this is an oversimplification. Open Source was mainly a backlash against the viral clause in the GPL advocated by the FSF, which was difficult to live with if you sold software for a living. The FSF had some story about a service related way of capitalizing on GPL software which always sounded like an afterthought excuse to deliver when GPL was called business-unfriendly.
So people wanted to collaborate, just not on FSFs terms and vision.
Yes, there was the LGPL, but it was weakly advocated in the beginning, and shared the name with the GPL which was considered a poison pill. (and not just by Microsoft, as revisionist freetard historians will want you to believe)
And this was not just about the suits, it was for the self employed developer too. Even more so, since big business was more likely to have a service organisation in place. (queue IBM that promptly invested heavily in Linux)