" rather than concentrating on the point I made [physical presence]"

A method for surveilling people's activities ideally has these properties:

1. Delivers intel on as many targets as possible.

2. Requires little to no effort on operator's part.

3. Is easy to deploy multiple times or stays persistently.

4. Doesn't reveal presence of surveillance.

5. Takes a lot of work to avoid.

6. Has reasonable cost.

A method for concealing communications or activities has at least these properties in this order (except for 5 which always helps):

1. Prevents detection of activity entirely against likely eavesdropping methods in use.

2. Makes the eavesdropping difficult to attempt

2-1. Focused instead of mass surveillance.

2-2. Expensive.

2-3. Physical.

2-4. Requires talent instead of brainless drones.

3. Increases odds of person being surveilled detecting the surveillance.

4. Allow for countermeasures to end or recover from the surveillance.

5. Is deniable and inexpensive.

So, let's look at average person using common recommendations. The average person will be using Torbrowser, TAILS, Windows + Tor, Mac + Tor, Linux desktop + Tor, or main mobile OS + Tor. They will not be professionals at attacking or securing systems like the criminal or government hackers tasked with uncloaking them. The attacks on Tor, by NSA & by academics, apply where many users get unmasked remotely in a way they never see. They can all be surveilled at once by NSA's existing infrastructure. Outside this, the FBI deanonymized users by using a browser 0-day (endpoint attack). Five Eyes, esp NSA, have 0-days on each desktop and mobile OS with high, market share per leaks. We regularly see Russian and Chinese hackers breach them in the news. We also see all kinds of hackers breach systems in general plus lots of bad decisions by users. The risk of a stealthy, mass, inexpensive leak of people using digital communications is very high whereas the odds of them outthinking average surveillance is low and targeted hacking very low.

So, let's look at people using meatspace with methods like I described above and simple guides on their use. They've spent their whole life learning how to tell when people are watching them, nervous, or just acting unusual. They have numerous ways of blending into a crowd where WiFi or drops are available but with limited camera coverage. They can learn the traffic patterns of the area to see if anyone sticks out. Likewise, there's private spots to stash a long-range antenna and camera to do the same from a distance. Many know how to ditch evidence or pay for stuff with cash. Keeping their name and I.P. out of it reduces odds they'll be seen where no tech or HTTPS-style comms increases odds surveillance ignores them entirely as mere Internet, background noise. These methods were and are used successfully by many crooks and spies... today just like decades ago with drops, radios, and countersurveillance... while "smart" people, their OS's, and anonymity software get owned on computers quite regularly.

So, the average person looks to be better off avoiding the Internet, executable media, or anything that draws attention when trying concealed communication with other average people. It's easier for them to follow this advice like that than learn arcane, technical information that changes constantly. It also turns inexpensive, stealthy, mass attacks into requiring footsoliders focused on one person or a small group at a time risking detection constantly. That's also with no guarantee they'll keep whatever gains they acquire in intelligence collection. That's a significant increase in effectiveness versus new methods where you trust things that can be and are often invisibly hacked by remote attackers.

"When I go out, I can never be confident I'm not being followed, recorded in various ways or leaking biometric evidence. Online, I can operate with an assumption of full compromise _and still come up with useful OPSEC strategies_."

No you can't. If you can't trust or mitigate physical risks, then you can be compromised in the physical realm to defeat your software countermeasures. There's whole Snowden slides dedicated to those things. Not to mention books by experts in hacking, black bag jobs (esp TSCM), infiltration (esp spec ops), and crime (esp B&E's or cons). Physical security and lack of subversion is a prerequisite for and/or major part of online security. So, what you're really doing is hoping you're not worth their time or money at all plus no flaws are found in your hardware, firmware, OS, browser, Tor, or any other running software. Might be true but lots of counterevidence on software side. ;)