From my understanding, it’s probably multiple factors, including pushing users back to their app so they can track more and server more apps (3rd party apps usually block apps). Another is de-freeing the API access, which effectively kills many 3rd party apps in reddit case. The charge for API access is possibly very tied to the rise of data scraping demands for training AI models, and reddit has a lot of good content.

Essentially it boils down to - ways in which they can turn users into money.

• Control the content you see - Especially ads which provide income. Also injecting posts into your stream regardless of preferences to direct views towards sponsors preferences or to try to extend engagement.
• More visibility over user activity - It gives them better tools to manipulate users habits (that pesky engagement), and better (for them), user telemetry can be sold (people who like X like Y is useful knowledge but it can go far deeper than this).
• They want to discourage content that discourages advertisers - mostly this is NSFW content (since the advertisers don’t want their ads showing beside NSFW content) but I expect it’ll begin to span more than that over time.

With the elimination of third party apps, you can bet that ‘old Reddit’ is on the chopping-block soon too (mostly to boost ad views)

Remember the adage: if you’re not paying for it, YOU are the product.

I believe there is a push to reduce/cut out 3rd party apps so that the “parent” site has more traffic driven towards their official app, so that they have more data (ie, the value you as a user provide to them) coming to them directly.

I feel like this is going to happen more and more with these companies in order for them to extract as much value as they can, thsu ensuring the Enshittification of the internet in general.

In general it’s because it’s difficult or impossible to fully monetize a user on a third party app. This could be because the API doesn’t serve ads (like Reddit) or because it’s harder to track and harvest user data when they are not using a first party app.

Essentially, platforms like Reddit make deals with advertisers that they will display an ad in a certain format near certain types of connect (and away from other kinds) and will show them to users with specific interests. They can’t really do that if the user isn’t coming through a platform the company fully controls (so their website or apps). On top of this, their apps are designed to keep you engaged as long as possible and to harvest as much information about you as they can without you getting upset and leaving. This lets them target ads more specifically (which means they can charge more for them) as well as sell that data to brokers for even more money (who then sell it to advertisers). It’s all about how to best turn your attention into money, and a third party app doesn’t allow that (either at all or as much as a first party experience).

Reddit specifically also wants to sell access to their data to companies like OpenAI to train large language models as additional revenue sources, to do that they need to lock down the API used by apps to work with the platform.