I also thought that was true as well, until recently where I got to try out maribel myself in dmm's daily revival.
She is HIGHLY situational, is the best way to put it.
Her normal stats are even worse than leeanne's, a silver unit.
And the waiting time for her ability has forced me to dismiss her early more than once.
That shit is scary.
Well, i guess it wont matter to most newbies till her revival comes and they can test it themselves.