The Quad is not for everyone (but most regular consumers will be impressed). There are obvious input and output limitations. No expandability beyond the sub offered by Sony. Etc...
However, these days, the average joe consumes everything directly from the Internet. So, if you are one of those folks that can live with a combination of one device (say an Apple TV, PS5, etc...) connected to the Quad and the rest connected to the two to four inputs on your TV, then most of the connectivity issues are somewhat resolved (yes with limitations).
If you haven't tested the quad in your own room, making assumptions about the sound it delivers, is just an exercise in sticking to what you know. I just finished testing the Quad with an SA-SW5 sub against two 7.1.2 receivers working with B&W speakers. The sound field was superior in the creation of a 3D sound dome. Voices were extremely natural. Objects were all very detailed and well separated. Music sounded great with a convincing natural sound stage that was not at all gimmicky. Overall, it did most things well.
If you are an experienced audiophile, this system is not for you. I was very frustrated with the lack of controls to fine tune the sound. The subwoofer is insufficient for my listening preference in a large living room even at max. Given those limitations, it is the most impressive home theater in a box that I have tested (that includes the Samsung q990c, which I also had in the room). The Quad's ability to tune itself is uncanny. Setting up your own high end system to compete with the quad, will take even an experienced audiophile a considerable amount of time. Sure, you can get fuller sound, better acoustics, etc, but man the Quad is so good that I would recommend it over a real home theater for most people (because most are not audiophiles).
So, if you know someone that wants great sound, but doesn't want to work hard for it, or if you know someone who wants the system to almost disappear in the room, then the Quad with the sa-sw5 is the way to go over a soundbar based system.