if so, why stakes are not included?
Honestly, Stake is primarily known as a casino site and the sportsbook section was recently released which is why not many gamblers know about it. On top of that, there are a good number of issues related to their sportsbook like the following:
1. Their odds are pretty bad majority of the time due to high margins
2. Bad lag can be encountered regularly especially when placing accumulator bets
Well, the sportsbook is still new, we can expect some minor problem, but I am confident they'll improve in the long run.
They have the reputation so they can use their name to attract more gamblers, for now, I am still seeing people sharing their bets, so I was expecting they have a good experience using the stake sportsbook.