I'm still not certain what your overall question is, but I can explain $env_config['disable_all_tracking'] = 'y';.
$env_config['disable_all_tracking'] = 'y';
Is part of ExpressionEngine's option for Handling Extreme Traffic. If you
disable_all_tracking then you do not have to individually set the options for:
$env_config['enable_online_user_tracking'] = 'n';
$env_config['dynamic_tracking_disabling'] = '500';
$env_config['enable_hit_tracking'] = 'n';
$env_config['enable_entry_view_tracking'] = 'n';
$env_config['log_referrers'] = 'n';
disable_all_tracking option is generally set to 'n', but if your basing it off a master config that is trying to maximize performance, then it would be set to yes.
These options are best used for traffic spikes or sites that are constantly hit heavily. For your average site, having tracking on is fine, and will provide you with a variety of information that can be used to help you measure the site's success.
But, many of these details are also provided by Google Analytics (GA) and content delivery networks (CDN), such as CloudFlare. So as long as your site is configured to use an analytics program, those details are still available to you, just not via the control panel.
Some developers leave this variables on by default, and I know others turn them off by default, so that is up to you for the site your building or managing.
Also if you need to deal with heavy traffic sites or just want to make a site that performs better, add Solspace's Website Performance Guidelines to your reading list, and take a look at some of their performance enhancing add-ons. You can also take a look at Matt Perry's Make EE Faster presentation.