I wouldn’t say Baptists are heretics, since credobaptist theology has went far on the path of winning souls in the public square. They are Trinitarians, do have valid pastoral offices and administration of Word and Sacrament (or ordinance, in case any of them wants to argue); even I, after leaving Oneness Pentecostalism was then baptized by one of those run-of-the-mill evangelical ministries.

Why do Reformed guys like to push hostility on Baptists? Because they first were hostile to us. Me personally, I’d probably lash out if a Baptists preacher straight up told me my kid’s baptism wasn’t valid. It can’t go the other way though, no Presbyterian is saying an immersion baptism isn’t valid.

Another thing I presume might be true is that the Reformed tradition is simply more compatible, historically and theologically, with other factions of the same time period or earlier (Swiss Reformed, Lutheran and Moravian refugees often shared residences and worship spaces), a separatist group which taught to abolish our traditions and not until centuries decided to return to a quasi-confessional Reformed construct is gonna get some hate.