I came to Pharo after the fork from Squeak. What I have picked up is that prior to the fork, there was significant tension between those that wanted to maintain backward compatibility and those that wanted to move the language forward. The latter group forked Pharo and that statement was Pharo seems to have be a response to their previous repression. In practice it hasn't yet diverged greatly.

However one novel thing Pharo has added is Slots... http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.653...