No disagreement here ....thing is requesting information from a site requires a routing path(s) back to the requesting entity so even when/if all other undesirable leakage is stopped the site owner/information provider still knows that information was accessed/distributed - so depending on how much effort they put into it could be followed without touching anything you have any control over. Then there's also the fun of what all the the hardware pieces might be doing as part of their regular operation (which gets really interesting when dealing with safety-critical systems where even intercore interference on multicore processors could be an issue). From what I've seen very few people (to include the engineers & software developers) ever have full understanding of they systems they design/build. ... so I'll definitely not claim to do so even for systems I've had to get intimately familiar with - particularly since many of them are frequently changed/"upgraded"....
...but most of this gets rather academic as most users can block out most common tracking, but stopping absolutely everything? That'd seem rather unlikely.... particularly if the communication path remains entirely terrestrial-based (or using TCP). So yeah, most can be stopped as it's generally "cooperative tracking" (even if the user isn't aware or consenting) and for most people that's probably going to be good enough. I would expect anything more than that to start involving things that are outside the interest of most users (along with those doing the tracking) as the information gained wouldn't necessarily be worth the effort required to obtain it....
When even air-gapped systems can/have been tampered with it'd seem pretty unrealistic to expect that a continually connected device can't/won't be tracked to some degree ....if the information gained is worth the effort. ...but again that's getting into things that (currently) are unlikely to be an issue for >99.9999% of people.... (e.g. everyone who doesn't need to realistically worry about being targeted for capture/elimination by a world government due to past actions taken probably doesn't need to worry about being tracked via most of those methods)
...which is why IMHO it's generally not worth worrying about it too much (e.g. not beyond blocking the annoying advertising tracking from entities you don't have direct commercial/business ties, or regular scam artists/spammers/criminals)

... well, unless someone wants to make a living being a software/systems bug hunter, "white hat hacker" or IT specialist for entities with higher value information than most individuals have because if the rewards aren't worth the effort......
So yeah secure browsers and firewalls go a long way ... a person just needs to decide what's secure enough for them (which should realistically consider what sort of threats/problems they're actually going to need/want to prevent). :confused3: