In case anyone is wondering, here is my reply:
If you mean dome tweeters, nope, they are directional, eventually.
Worse, some suffer from resonance on axis which is dealt with nicely
Now, the issue next is lobing. That is, how the tweeter's response adds or subtracts from the next driver down (in frequency).
With traditional multi-way speakers with a tweeter on top, a mid or
mid-woofer below it, the sound is pretty good to the sides and below,
but not so good on top.
Take a look at figure five in this review. Notice that at 4 kHz or so
there's a significant dip at 15 degrees above axis. It's a little hard
to see, but the reviewer put the cross hairs right on it.
Now, compare that to the chart above it, figure 4. To the left and
right the drop off is equal and smooth. Further, note how much the top
octave drops off axis. This is normal, off center response for this type