Yes. But it quickly activated a ton of people who had zero previous interest in politics or culture wars. And it codified the tools of the alt-right, from language, to brigading, to harassment techniques, which within months spread to every single other medium from books to television, and around a year in became the most visible form of online right-wing discourse.
I don't buy it when people say GG was some isolated gaming-only thing. You're being disingenuous, or you never really followed what was happening. Three years ago, communication online looked entirely different pre-GG compared to how it does now.
Before GG, this entire style existed in the limp-dicked corners of the MRA/MGTOW/Red Pill world, completely powerless to affect the discourse. After GG, and all the mainstream coverage it got, everything changed. These people are now the loudest voice in America. GG gave them the template to achieve that.
The Tea Party was firmly engaged in dogwhistle politics. They attracted racists looking for a home, but not really much beyond the usual Southern Strategy pandering the mainstream GOP engages in.
They were also far more interested in actual policy. Unrealistic, idiotic policies, but policies nonetheless. Above all, their goal was to dismantle as much of the federal government as possible, and cut as many taxes as possible including things like the tariffs Trump supporters are so interested in.
There's overlap, sure, but I don't really think the two movements are outgrowths of the same thing. Few Republicans wanted Trump out of the picture during the primaries like Tea Partiers did. They're all about ideological purity.