thats when you talk to people that just go based off of limited experience with no actual practical knowledge and experience on multiple setups or the understanding of cabin gain, overall vehicle acoustics. In a hatchback or trunk, sealed is fine you have a proper loading wall, you have distance for the wave to propogate after reflecting off the loading wall and develop into a full bodied bass sound. In a trunk however, there's literally not much room for the wave to develop nor is there a good loading wall to reflect off of. Sealed is generally the absolute worse type of enclosure for a trunk unless you completely build a sealed off wall like those SPL builds, thats actually the best SQ you can get because its perfect phase however no one wants to go that extreme.
What this all means in actual real world results. Every truck with a sealed box literally has either weak bass thats less loud than the door speakers because of all the cancellation that goes on in an up or downfire configuration or the bass is overly midbass heavy because trucks peak pretty high and you have no deep bass. Most of the times its "you are lucky to have any bass to begin with" scenario thats how garbage of results you can expect with a sealed box in a truck. Every vehicle needs a perfect enclosure suited for how it is. Its not one box fits all
So whats the next best option that retains usability and gets decent results without needing to go all out? where's a good loading wall? The answer is a ported box with the port on the side loading off the rear door. like in this video right here