Aside from the suprise that someone feels so strongly about other people's music that they have to announce this feeling to the world, I had to chuckle, because I had just spent the weekend up in Vermont listening to a friend of mine create music using nothing but a computer.
Any one with an open mind will tell you that using drum machines doesn't by default make soulless music. No, making music without soul - or as I prefer to call it: crappy music - is exclusive the fault of the person programming said drum machine. In fact, some of the best music I know relies exclusively on drum machines. Try listening to Aphex Twin with an open mind and then tell me that drum machines have no soul.
Now, having said that, I suspect what the driver of the car meant is that drum machines have no energy, or, utilized by someone with no skill, can be static at best. Two examples from two different genres:
1. Susumu Yokota. A lot of his music is fascinating, especially when he plays with reverb (see Sakura). However, many of his songs are marred by the fact that the sounds he's coaxing from his drum machines can't ebb and flow like his keyboards. Listen to "For the Other Self Who Is Far Away That I Can Not Reach" off the excellent Love or Die album and you'll see what I mean. The dynamic piano and singing guitar are marred by the dead drums, thudding along with no sense of interplay with the rest of the song. What is supposed to be a crescendo bridge in the song is rendered absurd by the drum machine at the 2:30 mark.
2. The Who. For a band known for their energtic drumming, the decision to use a drum machine when recording most of hteir Endless Wire album is mystifing. While never destined to be a masterpiece, promising songs like the magestic "Mirror Door", where the music soars and Roger roars like the Who of old, falls well flat of what it might have been due to the drum machine not able to change and play off of the song's energy.
So: to me, soul being a function of skill and passion, not insturmentation. Or put another way: Form not Function. Or put snarkily: Peter Cetera played with real drums: what's that tell ya?