But is that at the expense of frequencies NOT at the targeted port frequencies?
It is. As mentioned each has their trade offs.
It is if you're running the sub well below the box tuning frequency. But if you're not there is no trade off.
The quibbling over which is better for what is just that, quibbling, and is usually the case the more vociferous the quibblers the less likely they are to actually understand what they're quibbling about.
Hence why in my car I have a sealed sub setup and in my Living room I have a ported sub.
There is a reason why you might have that preference, it's called Cabin Gain. The smaller the listening space the higher the low frequency cabin gain, which would make a sub with flat response in a large room too bottom heavy in a car. To compensate for that you can use a small sealed sub, one that would be very shy in the lows in a large room, but with the cabin gain of a car it's just right. This JBL data sheet shows response of the GTO 1014 driver in a small sealed box both in and out of a car:
It also shows vented and bandpass boxes in and out of the car; the sealed is best, despite being the smallest of the three. But one can't draw any finite conclusion from this one case, other than how a sub will work is a product of the driver specs, the box and the room you're using it in. Use another driver with different specs and the results will also be different.
Designing a sub is like juggling three balls, as you have to consider the driver specs, the cabinet, and the listening room it's intended to be used in. You may end up vented or sealed, or with something else entirely. But what you don't consider is the program material, only how low and how loud you need it to go, and how to get that with the driver being used.