For a long time Tableau Server was available only for Windows platforms. But with the Tableau version 10.5 there was an introduction of Tableau Server on Linux. Basically, now you have more flexibility with Tableau Server. Some organizations prefer Windows, whereas others consider only Linux. In addition, it depends on the culture of the organization and the available resources to maintain and support Linux or Windows servers. For sure, using a cloud environment will simplify this.
Tableau Server on Linux makes Tableau products more agnostic. Moreover, it increases the security of deployment and decreases the cost of ownership.