Porting main speakers is a much different proposition than subwoofers with ported enclosures.
Biggest reason is the x-max is much less (distance a driver piston is allowed to travel) on main speakers and is easier to to control the motion with the driver's suspension.
Lack of control of driver excursion whether main woofer or subwoofer causes distortion.
Most main speakers are ported because they are more efficient and extend deeper and the slight additional distortion is a worthwhile tradeoff and not audible.
The main reason I prefer sealed subwoofers for music is that they have significantly less distortion than their ported counterparts, especially where it matters most in the critical 25 to 80 Hz region. That distortion can cause coloration that can veil the midrange frequencies- not good if you love vocals and clarity.
Ported subs work well for home theater because the additional distortion is not so noticeable in a typical effects sound track and the additional efficiency and extension is more useable. Also midrange clarity is not very high on the list of home theater system users.
Again, distortion at critical audible frequencies that can veil the midrange with ported subs is the main reason to avoid them for music.