I read your link. Unless you want to call all persons or (small) groups who dissented from Roman doctrine in any of myriad ways, "Baptist," there is no unbroken link of people who believed in immersion baptism. Some who believed in immersion, also believed what any believer would call heretical beliefs too. Wickliffe, Hus, Tyndale, were all heroes in faith in Christ--but not Baptists, sorry. Baptism became an issue AFTER Luther, as the Anabaptists were the left wing of the Reformation. Luther saw their "fanaticism" as destructive as the Roman corruption. Luther himself allied his church with the state, but in no way allowed it to be controlled by the princes. It took later Lutherans to do that.
The Roman church always had dissenters, but until the Reformation, their beliefs were not uniform, nor were they anything but few. The Church and King burned anyone alive who would dare openly criticize Rome's hegemony.
While I believe there has always been a faithful remnant in the Church, they weren't necessarily Baptist in belief. The only scholars who teach that there is an unbroken chain of Baptists are, ummmm, fundamentalist Baptists, for some reason.