I can’t say they weren’t counting startup denominations that gained from recent divisions in other denominations, but perhaps there was some establishment date they were using.
Sort of like batting average in MLB requiring so many at bats to qualify for the race.
I think you can see that if I start a denomination tomorrow with just me and have 7 at the end of the year that I’ve just experienced 700% growth.
The PCA is not just a startup. They have been around since 1973 (42 years) and was founded as an alternative to the churches no longer teaching the Bible as the true Word of God, and Christ as the “way”. Folks who were tired of their “dead” churches moved to the PCA, and continue to do so.
Your analogy of 7 growing by 1 to be 700% is ridiculous. The PCA has grown by thousands of people, as are other true evangelical denominations who are truly teaching the Bible. We may never reach the massive numbers of your RC church, but that is NOT the point.
You may want to read up on Revelation chapters 2-3, John’s letters to the churches. These “churches” not only represent the actual named early history church, but also are a picture of the types of churches throughout the ages. Then you need to ask yourself which of these churches speaks of YOUR church? (I would be curious to know which one you think is yours) And then which churches does God rebuke and/or deem “dead”.
And please do not tell me that these churches all represent various stages of the RC church because it is the ONLY church. There was no RC church with its ecclesiastica at the time John wrote these letters.