and take control of these sorts (sports?) teams?
Speaking specifically for the NBA, my favorite sport and one I spend quite a bit of time investigating the sports history surrounding the league, you may have mistook the trees for the forest on this one.
There are 30 NBA teams as individual companies, each with an individual owner as it is against the rules to have an ownership stake in more than one franchise. These 30 owners* make up the company called the NBA. The Commissioner of the NBA is appointed by the 30 owners and he/she works for those owners.
*For simplicity sake, we will imagine each NBA team is one single owner, it's often more nebulous than this but this is just to illustrate a point.
In 1946, several major ice hockey arena owners got together and formed the BAA (Basketball Association of America). In 1949, the BAA absorbed one of its competitors (the National Basketball League) and became the NBA as we know it today.
During the following decades there were several expansions and mergers including the absorption of the ABA in the 1970s to form the ultimate professional basketball league in the country. During this merger the majority of modern NBA teams not already in the league were acquired. A few teams were added over subsequent years and have moved to different cities such as the Vancouver Grizzlies relocating to Memphis or more recently the Seattle Supersonics becoming the Oklahoma City Thunder, but the league has been set at 30 teams for a few decades now and I doubt they will contract any time soon.
We may see a team in Seattle again in the near future in the next expansion but I'm not sure if/when that will happen.
Hope this helped!
The NHL is the result of nearly 30 years of development in hockey in Canada, and a further decade before it consolidated its position as the unparalleled top league.
Though the NHL was formed in November 1917, there had been an organised hockey league in Canada (the US wasn't a factor until the mid-1920s) since 1886. These were strictly amateur leagues until 1907, as the social custom of the time called for only amateur athletes.
Now, I won't get into the details on the various reasons for the formation and dissolution of these leagues, though if someone does want to hear about it I will gladly do so.
But for what matters here is after 1907: amateurism had slowly been giving way to semi-professionalism, and in that teams began to openly pay players. This went against the social custom of the day, and led to a split amongst the owners. The result was in 1909 a new league was formed that was explicitly professional, the National Hockey Association (NHA), the direct forerunner to the NHL.
The NHA lasted until 1917. It met its end due to a combination of the First World War taking an effect on both the availability of players (many were either enlisted or conscripted; in fact the 1916-17 season had a team from the Canadian 228th Battalion play, who were quite good; more on them in a moment), and the opposition to one owner, Eddie Livingstone, who owned a Toronto-based team.
So during the 1916-17 season, as noted, there was a team from the 228th Battalion. However mid-way through they were shipped overseas, which caused havoc with the schedule. Suddenly there was an uneven number of teams, so the other owners decided they would suspend Livingstone's Toronto team. It was an easy choice for them, as they had a less than cordial relationship with Livingstone, who had made enemies a few years prior by owning two Toronto teams and refusing to divest himself of one of them before being threatened.
To avoid him completely for the upcoming season, the four remaining teams met on November 23, 1917 and created a new league, the National Hockey League, explicitly to keep Livingstone out. Though he sued them over this, he lost and after several further attempts to establish a rival league, faded away.
I'll also note that on the West Coast, there had been the Pacific Coast Hockey Association (PCHA), which had been around since 1911, and competed every year for the Stanley Cup to see who would be the Canadian champion. However that league, which was renamed the Western Canada Hockey League, and finally just the Western Hockey League, ended in 1925, leaving the NHL as the sole top pro league in North America, which despite challenges throughout the intervening 90 years, it has held since then.