I mean the dev is obviously free to work on whatever he wants, but I've had a Tildes account for like 2 years now, and honestly it never got any traction. Lemmy on the other hand is getting a lot of users, and it is desperately missing a non-buggy app.
I'd already been working on a Tildes app for a while before knowing Reddit was going to kill third-party apps. I didn't have time to work on Lemmy and Tildes and RIF.
Since Tildes is different enough, it made sense at the time to have both a Tildes and RIF app which didn't have too much overlap; their communities are quite different. Lemmy and RIF are more similar to each other.
Who knows; after I release my Tildes app, I could work on other apps too.
Probably believes in Tildes more. Which is disappointing, because Tildes is less of a social media platform than it is a gated neighborhood. It doesn't want to be reddit, it wants to be a club.
As somebody who has been bouncing around on alternative social media sites for years now, an app is not necessary. If you design a good website, your website can be used in a browser - even on an older phone with depleted battery capacity. Although there are mobile apps available for Lemmy, I have always been able to use it just fine in Fennec (F-droid packaged version of Firefox). Compared to Lemmy, Tildes is blazing fast in a mobile browser. The same goes for Mastodon, where I find the web interface to be superior to any app I have ever tried.
From a technical standpoint, the scope of the Lemmy project is much larger than Tildes. Tildes was started by a (understandably) disgruntled Reddit admin who wanted to raise the quality of discourse. Lemmy was started by a couple communists who wanted to create a tool which allows internet communities to have a shred of autonomy. To me, it seems much more practical to build tooling on top of Lemmy than Tildes (I say this with no disrespect to Tildes. I was around when it launched, and have generally positive feelings about Deimorz. MUCH better feelings than some of the other Reddit clones).
The idea to do a Tildes app at this moment seems silly, but only a little more silly than doing a Lemmy app. These apps are neccessary for Reddit because Reddit is a giant steaming pile of shit. In my controversial opinion, doing this for the Fediverse is cargo-cult behavior. People are doing this because they are deeply programmed to believe social media platforms are deliberately designed to exploit them (no wonder why). Third party apps were used to wallpaper over the problems that these corporate platforms refused to fix, but with AGPL licensed federated platforms, we can fix the problems right at the source, or fork the project and run a better instance (but preferably work with upstream and improve the experience for everybody).