The Problem
The biggest problem with the 'trying to do reform online' is that people are physically separated from each other, and most traditional protest is physical.
Short list of traditional stuff we can still do:
Voting
Informing of protests organized by others
Sending letters
Sending money
Less Traditional Solutions
Getting to the same location: At a bare minimum, some kind of code to find out if there are other people in your area. That there is some population clustering strikes me as quite likely actually, even under random chance you get clusters.
Mutual aid at a distance: People could try mailing goods to each other, or figuring out who is on the edge of the range they are willing to drive to once a year and occasionally meeting up to exchange gifts like canned goods. I've been thinking the usual method of trying to rely on local groups just isn't very effective - what if your local group doesn't exist or isn't accepting people? That actually happened in my case when I went to look at a local mutual aid group.
The oncoming climate disaster: I do not have a green thumb, but I would love a project to green things. I suspect a lot of people wouldn't mind having their walls turned into mini-gardens but don't have the skills (or resources) to really maintain it or start it. Efficient use of space could mitigate the fact land is expensive. If global warming really starts baking plant life too, it may also be a good idea to start practicing in-door basement gardening (perhaps try to make much deeper basements for natural cooling?) sooner en-mass rather than later (which could lead to mass starvation if put off).
Pure Online Actions: There are some forms of work that lend themselves really well to being online. Coding, writing, news, encouraging people to vote, sending money to workers on strike.
and finally...
Cutting the pigs off directly: I firmly believe the most effective way to combat unethical companies is simply to start and support worker owned companies where every employee gets a vote on their wages, and 'starve' the big companies. I found myself looking at the massive amounts of money raised and wasted in political campaigns by small donations and found myself thinking - damn, with a million dollars, you could start a really small company with that. The second most effective way is probably striking, which, yes, you need people on the ground for that.
We could use an ethical version of Amazon, with a collective of shops that people can visit (the offline side of warehousing is a whole other bundle of issues), and an ethical Paypal. I know that credit unions exist, but I don't know of any credit union that has a Paypal-like API and easy convenience of simply clicking to pay for things. Uber and other apps. There is a huge amount of labor that we could 'take back' simply by providing another venue for people to practice it. Unfortunately, I don't think the fediverse way of doing things is quite appropriate when it comes to systems dealing with money. It's one thing to duplicate posts or ads for content for sale, but you don't want to duplicate credit card information. Open source it maybe and use 'semi centralization'; the Paypal-esque site can handle logins and money, and the Amazon-esque sites can perhaps do some form of federation and handle actual showing of items.
I believe they were using it as an example of failure to corner the market, that is, in reply to the previous person's comment and not directly to the main post.