You never established the context of these quotes, asygo. Give us some examples of doctrines and practices that SDA's kept for a long time that turned out to be wrong.
If you want more context, the references are there. But does anyone believe that there is any context such that we can conclude that we are infallible?
You ask for examples of SDA errors, as if our existence was not closely tied to an error in interpreting Daniel 8:14. So let's start with the erroneous belief that cleansing the sanctuary meant purifying the earth by fire. True, that was in the 1830's and 1840's, but that just shows the fallibility of our founders. I don't know anyone who believes they became infallible 20 years after that.
Then there's the Shut Door - that the door of mercy was forever closed to the world in the 1840's. That was wrong.
Several prominent leaders and members believed that there was a time long ago when Jesus did not exist. Some never accepted the truth about that.
There was a time of confusion regarding Sunday vs. Saturday as the Sabbath. Once Saturday was settled upon, there was still disagreement over the exact time to start.
I'll stop there. Just let me know if you need more proof of human fallibility.