That's because they were usually half-baked attempts that got obliterated in the market compared to the Apple product who went on to become the market leader in its category for years on end.

E.g. the sales of any smartphone before the iPhone compared to the sales of the iPhone. Or any mp3 player before the iPod compared to it.

And serious competitors took a while to arrive. It took several versions of BS mp3 players to get something like the decent MS offering.

The first Android phone was released one full year after the iPhone, and it took it several versions to be competitive.

With tablets it was the same. Compared the dreadful, lackluster selling, offerings before the iPad. It took them 2-3 years to even come close.