I respectfully disagree. While true that Houdini was one of the first visual effects softwares offering an indie license, it was by no means the only one. Substance comes to mind, before the Adobe acquisition.

The timeline is also unconvincing: a considerable number of years elapsed after Houdini entered the market and Autodesk/Maya offered an indie license. However, is does coincide with better blender documentation and rise in YT content that rapidly grew the blender community.

Houdini can do more than FX, sure, and I've consistently heard nothing but good things, but its professional use remains relatively [edit: departmentally] niche. So, it may seem to someone in the niche of FX that Maya is losing ground to Houdini, but on a macro level Blender has the features and price point to threaten a larger portion of Autodesk/Maya's market share. In lieu of better data, I'll refer to google trends of the three softwares in which Houdini is a flat line at the bottom. I will gladly consider data to the contrary if you have it.

Either way, my main point was that competition is good, and who is responsible for how much doesn't change that.