So there are a couple of things to be addressed here:
First, I do think that Fitbit, like many other companies, test out their products to meet all required quality standards: they offer you a warranty for a year, and, should the product fail on you (depending on the case) they actually replace it without hesitation. I do believe that they have normal/average people or users test them out, it’s what’s called field testing I believe.
Then there’s something about the bands. Yes, they do have an issue with the bands: they bubble, they peel, the tear apart, etc. But that’s something that you need to be conscious about. If you take good care of it, clean it the way they tell you to, it’ll be fine. I have owned a Fitbit Charge, a Charge HR, a Charge 2, a Flex 2, and a Blaze. The major concern was with the Charge and Charge HR since they did not have replaceable bands, which they have improved with the Charge 2. Now, there are things that I have notice that do tend to have impact on my trackers: exposure to heat, like when I’m cooking, or exposure to moisture when I’m gardening. I did call their customer support and they kindly replaced my Charge back then because eventhough I thought that it could take stirring some pans or plowing the dirt and sticking my hands into gloves that got wet gradually, they did point out that it could do some harm, and I think they’re right if you take into consideration that it’s designed to track your fitness activities and, since it is an electronic device continuous exposure to “normal” or “daily” activities may be the issue. It is not intended to be used as a “watch”.
Now, regarding the accuracy of the device: the software or the algorithms seem to be on point in my case, but that’s only because I have taken the time to explore it’s settings and readjusted my stride length, both for walking and running, and ever since it seems to be at least 95% accurate, which is basically outstanding given the fact that it’s a wrist-based tracker and not a hip or waist based one. I can imagine why it won’t track your rowing eventhough it is a very common exercise, but depending on the tracker that you own that’s how much information you’ll get; you can’t expect the same information from a Charge than from a Blaze. The newest models do have some preset exercises that you can choose from so as for your Fitbit to track it in real time, for example: if you’re going for a run, even without the connected GPS feature, it’ll give you your current HR, the amount of steps, your calories, and all the basic info, along with the pacing (for Blaze and Charge 2 at least), and I find this pretty neat and reliable since I know for a fact that my steps will be translated into distance and then into pacing.
I’m a fitness trainer, and the only two things that are sometimes a little bit off are the HR (which can go +/- 5 or 10 beats per minute), and the calories burnt (which I believe Fitbit overestimates). But it’s sort of ok in a sense that it’s expected to be that way, a wrist-based HR monitor is not going to be as accurate as a chest strap, let’s not talk about a medical monitor. It’s supposed to give you an idea, or an estimate.
You need to understand that, as far as accuracy is concerned, you have to know what device suits your needs: if you’re a walker and a runner, then use a a hip or waist based tracker so as for it to track your leg movement, but if you’re more into things like elliptical, stationary, maybe orange theory or some other bootcamp or high intensity interval training, you might want to try a wrist-based tracker to monitor your torso movement.
Last but not least, everything gets a new and improved version, it’s called innovation. I’m not a real tech-savvy person, but I can imagine why they can’t just add things to older models: it’s like when Apple decides to deprecate support for your old Apple TV or for your 2nd gen iPod Touch, if you know what I mean. If the hardware doesn’t support the change, the you can’t force a software change.

I believe that if some people are willing to spend $700 for an iPhone or a Samsung phone each year, or every six months, a $150 fitness tracker is no biggie if you are to wear it for what it’s meant to be worn, plus, if you take good care of it, not only with cleaning it but with charging it, then it’ll outlast the warranty.
My advise to you would be not to expect much by knowing too few.

They also don’t cover all the keep fit activities, the worst thing is all you have to do is wave your arm and that registers as exercise, but it doesn’t register rowing, either on a machine or on water

I have had mine for 2 years now, I just use it when running/walking and even so its not that accurate

Just get things right before you release anything else, get them out for testing with the public, not in a lab somewhere

Just get it right before you release these things, then we wont need to buy the next improved version