Yeah, Masstree has settled into the standard set of comparator systems for most research since it was published - and not as a strawman "this system was crap, so let's pretend we've done good work by beating it!" but as a real challenge to do better than.
[1] https://rise.cs.berkeley.edu/blog/anna-kvs/
[2] https://github.com/fluent-project/fluent