Can't blame people for that. With the frequent Android security issues, it requires monthly patches similarly akin to Windows. If an HP device received a Windows update 8 months later than a Dell device, isn't that concerning? Imagine Windows 10 in that light. People were furious about losing the start menu button on Windows 8 before 8.1 brought it back in some facet.
Now, to put it into better context, some Android features increase longevity. Project Volta and other battery life software enhancements made up for battery degradation because they deplete over time. Before Lollipop, Android was even more problematic. Refinements are also important to the user experience. I am not saying Android O isn't as groundbreaking as other software updates, but it's important to get device support right. HTC was the standard bearer for OEMs when they self-imposed timeframes. Samsung is notoriously slow and even made a commitment to serve its unlocked models better.
Since the regular S8/S8+ MSRP is priced as a flagship, there are certain expectations that come with the phone. Software not lagging out of the box or in the first month is one of those expectations. When people see Apple offering device continuity and tremendous support, they could understand that Apple charges a premium while offering award winning customer service and reliable device support.
Samsung is head and shoulders ahead of its competitors in hardware, but can be very mediocre with software efficiency and support. If I wanted just one major software update at best, I might as well spend my $ on a Moto or OnePlus device. What's the point of extra features if a phone inevitably bogs down and lags? Samsung burned a lot of bridges with the Note 7 fiasco. Now, they're burning additional bridges with untimely/infrequent software updates after making a commitment. Let's not forget they could be cheating people out of their devices during device trade in promotions as well.
You cannot fault people for sticking towards other competitors because Samsung offers too much baggage for what device features and software features it has. With HTC, I know that I have cleaner software with Sense. With iPhone, I know I can use my device for two years with constant software support.
I cannot recommend Samsung to many people at this point.