What is possible, is near alignment. This is what is important. If you can keep sound sources within 1/4λ of each other, then they'll sum properly and won't exhibit frequency anomalies. This is possible, and it's desirable.

To tell the truth, most good loudspeakers sum true at least on-axis. If they don't, it shows up as a spiked dip in the response curve. But no loudspeakers are actually time aligned through the audio band. Use of the phrase "time aligned" is just sales rhetoric.