Right, but there are I think a few assumptions there:

1. You need to set up NAS and downloading software - that is not as trivial or common as HN audience assumes :)

2. You need a reliable and safe source of torrents. They may be paid or invite only, or may be super scammy and unrealiable and mine crypto etc etc

3. How safe do you feel in your jurisdiction/location at running plain torrents. Here you get notices and sometimes strikes / actions pretty quickly, so now we are talking at least a VPN, which is next layer of setup, configuration, possibly price, possibly its own threat vector as commercial VPNs are scammy, your own VPN is non-trivial to setup correctly.

etc etc etc :)

With synology the NAS and torrent software is pretty plug and play? I boot it up, plug in some hard drives, and click yes a bunch and it's there now.

Agree with 2 though.

(Note that this is perhaps magical thinking, but I would personally not be comfortable running torrents to "iffy" sites/locations/purposes, on the same primary storage array with my tax documents and family photos etc; my NAS is as local-network-only as humanly possible. That is a segregation and personal preference though, and does not detract from your main point)

2) as long as you are not looking for exotic stuff you can just use public trackers or semi-private ones (they require an account but usually you do not have to keep a ratio, do not need an invite and they do not require you to sell your soul to the devil).

If you want to go down this route (and you use *arr) prowlarr is a must have to avoid wasting time copying configs between the *arr.