You're absolutely right.
But let me give an example. In terms of FR, HD800 is closer to HEKv2. And very different from LCD-2C. But both HEKv2 and the 2C are planar sound despite the big difference. Very different from HD800. I'm not talking about the FR. It is more of the sound character or timbre. Planars seems cleaner, tend to smooth things over, have less decay. They just sound different.
Regarding the bass, people say planar has less bass impact. This is true if they're talking about mid-bass impact, as they are flatter in the low FR. But their bass is in general has fuller, heftier and more solid character, compared to dynamics. Just EQ up the mid-bass of LCD-X and see what I mean. That is the planar bass impact that I'm talking about. Some planars do it better than other planars, of course. Maybe I should use a different word to distinguish it from mid-bass impact, which dynamics tend to have.