I'm sure the poster didn't mean to say that every piece of gear sounds the same. That wouldn't make sense. I was commenting on how some players seem to say that every tonal variation that they could ever desire is available to them in their hands and doesn't depend on the effect of the downstream electronics. They're happy to go into an amp, the mixing board, whatever. The tone is "in their hands".
I do have a bit of a different take on your statement that: "And make no mistake...the way you play has everything to do with how you sound as a bass player." I agree that it has a lot to do with how you sound, but I don't believe it has "everything" to do with the sound as you claim. Play with a pick or play with your fingers, I know that is a very big determinator as to how you are going to sound.
With an unamplified or even miked acoustic bass I can agree with the statement that the tone is in the hands. However, with an electric bass guitar, it's a different ball game. There's just so much more going on in the downstream signal chain.
In my very rough estimation I think that how you play has about 1/3 to 2/3 to do with the sound. The rest has to do with the instrument and with the amplifier. Otherwise why would we have so many different types of strings, pickups, electronics etc. available to us if they didn't have a significant influence on the sound?