How is it guessing wrong? From your own words- there is a part of the Z faith that is welcoming to outsiders. There is a (im assuming larger) portion devoted to “keeping it in the family”. Thats like saying you cant be “part german” and be born in the 1930s-40s due to racism.
And words like “generally” aren’t exactly known for being *concrete* in evidence.
It’s guessing wrong, because in ‘the bigger Zoroastrian countries”, i.e. India, is where it is the most conservative & doesn’t accept converts or mixed mariages.
It is the smaller communities, i.e. U.S., Canada, and Europe, where that is primarily changing. And those changes are mainly among the laity & splinter groups, not the mainline priesthood.