Let's say you run a moderately successful flea market. You own a moderately sized field. You employ a staff of accountable organizers to vet and select your vendors to ensure they aren't selling anything you don't want at your market (say Nazi paraphernalia, guns). You have security staff and volunteers at the event itself to ensure vendors and customers are safe - they ensure vendors aren't selling anything they shouldn't be, they ensure customers don't try to steal or assault your vendors, they make sure nobody accidentally sets the field on fire, they manage the parking lot and portapotties.

A collective of artisans admire your success and buy up an adjacent field. While your flea market focuses on second hand and vintage goods, they want somewhere to sell handmade things. The organizers of your event work with the organizers of that event to share strategies and ensure both markets can reasonably remain safe and popular. Since they by and large hold themselves to the same standards as you, you agree to share a parking lot and build paths between your two fields.

A local farmers co-op eventually joins your meta-organization in the same way to offer fresh meat and produce.

Now you have a bustling megamarket. The billionaire that owns the local mall sees a drop in revenue due to folks going to the fields for secondhand clothes, fresh produce, and local art. People aren't shopping with you as much anymore.

The billionaire comes up with a plan to recapture the market. Open air markets in fields are popular now? The billionaire buys the rest of the farmland around your fields and flattens it. They pour a paved parking lot with a dedicated interchange with the local highway. They promise a mix of big corporate vendors and allow smaller vendors to set up their own tents and sell right alongside everyone else.

You think, wow this is a great opportunity to grow all of our markets even more. You start building pathways from your field into the billionaire's field so customers can easily get between your markets.

But soon, you start to notice something. People start parking at the billionaire's field because it is paved and has easy highway access. Some of your vendors have started pulling out of your markets so they can go set up at the billionaire's field so folks see their tent before they have spent all their money. Vendors who don't move start having to pull out as the market is no longer worth their time or money. With fewer vendors, even more people avoid your fields and stay in the billionaire's field.

And you start to notice something else. The billionaire started posting folks at the oath between your fields. Your markets have a few vendors the billionaire and their corporate vendors deem unsavory - erotic art, microbrewed beer, that sort of thing. They won't allow in any customers who have bought anything from those vendors because they run a family friendly establishment. Soon, the people who still come to your side of the field are avoiding those vendors.

You notice an additional thing. The billionaire isn't as diligent at vendor management as you are, especially with the amount of resources they're using making sure nobody is carrying around erotic art from your market. While the side of the field near the parking lot where all the corporate vendors are is bright and shiny, you've noticed some questionable things happening near your side of the field. The antiques dealer is selling Nazi paraphernalia. The information tent for the local gun club has started to sell firearms with no background checks. The carnival toy vendor is secretly selling opiates. Folks who shop there keep trying to get into your markets and your security folks are having a hard time keeping a handle on things. You don't have the resources to screen everyone who comes in. You end up having to fence off your paths to prevent folks coming from that market from causing harm to your vendors and customers.

But by this point most of your customers are accustomed to using the fancy parking lot and shopping with the corporate vendors. They're confronted with a decision: do they just keep going to the billionaire's field and get their clothes from the TJ Maxx tent or are they willing to make two stops so they can still peruse the cute vintage clothing?

Driving all the way around the fields to get to the other parking lot is pretty inconvenient so don't bother. Eventually you can't make the property tax payments for your field and you have to sell. The dream is done. The billionaire buys up the fields and expands their market.

Now rewind. You are an enthusiastic customer of the farmer's market. How do you feel about the billionaire's plan to buy up adjacent farmland?

(I was not able to work in a metaphor for meta "extending" activitypub with "new features" that aren't part of the spec and forcing the rest of the fediverse to comply or get left behind)