Yeah, I went through the motions looking for a good Productivity/Task Management App/Site in the past too. And nothing really did it for me other than Kanban. Found it through a Lifehacker piece that led to a YT vid on Kanban and extended to Kanbanflow in another sidebar vid. So I didn’t find it easily on google either. 
Those other Apps/Sites do have their uses for big projects/teams for sure. I know the StarCitizen Devs use Jira and it’s somewhat similar to the Blender Dev Portal. So for big projects and teams with lots of issues and tasks it definitely provides certain benefits & services.
But as a single user or even if working on small-medium group projects Kanbanflow, I believe can be extremely simple and straightforward to use. The timer helps keep me focused and a health reminder to take breaks so I’ve always loved that.
I used to keep a Pomodoro timer app on my phone every time I sit down so it rings 'n reminds me to get off my butt and take a break. But Kanbanflow helps to that + track the time I spent on a particular task, so it’s a Win-Win. Can’t do this job for long if you’re struggling with health risks by 40. So even the small things count. Especially when you’re working solo and can get sucked into your screen for hours on end.
The paid features for Kanbanflow seem to be really geared towards working with a team. Making it easier to assign tasks and share/track work, etc. I’ve never really had the need for it cause I use this for personal use. But at $5 a month, definitely seem affordable and I’m glad that package is available for users who need all that functionality, but also without taking away anything important from a free user. 
Totally agree with you. Sure, Project/Task Management Apps/Sites can be quite the fluff. (Expensive too.) But there is a reason big projects use them. And sure, as a single user or small team you might not require all those features but for me personally it helps keeps things in perspective when I’m working. When you can clearly see what tasks you have for today and what you have after that. Let’s you get to work and focus on working rather than spending too much time wondering what should I do next and after that and so on…
Love that Kanban board doesn’t let you have more than 3 tasks in-progress so you won’t end up overwhelming yourself with a whole heap of tasks and not doing anything. Was my struggle for the longest time. I just had to-do’s everywhere but couldn’t focus and get started on anything. 
Not to say everyone is like this. So if this sort of workflow helps you, then by no means should you not make good use of it. Some people use sticky notes, some use a notebook, some are just productivity beasts and can GTD just with a mental map + coffee.
Whatever helps you focus, get your work done and keep track of other members/tasks in a team. You should use it.
Good Luck with Your Life, Health, Work 'n Getting Shit Done LP. 