Reliability, future-proofness and simplicity.
Reliability:
Using settings files to change socks proxy settings is not as reliable as keeping Tor Browser as unmodified as possible.
TOR_SOCKS_HOST, TOR_SOCKS_PORT regression
Above was the original reason for giving up on modifying Tor Browser settings. Keep modifications of Tor Browser as minimal as possible. Differences are documented here: Tor Browser Essentials
Some users reported to have lost settings when they upgraded Tor Browser. This then also could break connectivity. Happened in past.
SocksSocket is nowadays Tor Browser default. It is prudent for Whonix to stick with the defaults as much as possible. The smaller the difference, the less likely are any Tor Browser bugs introduced by Whonix.
Tor Browser connectivity was bumpy during the first year of Whonix’s existence but it’s stable for 6 years now. My development experiences of 7 years Whonix maintainance manifesting in various design choices.
future-proofness:
Tor Browser was ported from using TCP to be using SocksSocket. Tor Project once planned to remove TCP support from Tor Browser to make it more leak-proof. (Tor Project has the perspective of a regular host operating system, not Whonix.) Their idea was that Tor Browser should only be able to talk to a unix domain socket file (provided by Tor) with no capability of system default TCP / DNS.
Simplicity:
When Tor Browser changes things, these changes are reported to and blamed on Whonix. Here are some examples:
- noscript removed from default menubar
- the default setting of the security slider being set to default rather than highest
- torbutton addon removed (was integrated into Tor Browser core)
- Tor Browser Error, perhaps from 9.0.1 update
- Noscript with Security Slider at Safest permits around 30 sites
- TorBrowser 8.0 high cpu usage while idle, in whonix
- Is anyone having white bars in the TBB? - Tor Browser Letterboxing