When starting out a new faction, it’s easy to get overwhelmed with options. When playing a faction you’ve known and loved for ages, it’s less common but still easy to get overwhelmed with options. One of the best things Privateer Press ever did with Warmachine & Hordes was to introduce the concept of theme forces. In MkII, these allowed you to build thematic armies based around a particular Warcaster or Warlock, limited to model choices that fit with the leading character or a point in their fictional history, but with additional perks and benefits to balance out the loss of competitive versatility.
In MkIII the concept changed to align with the subtypes of each faction, opening up a lot more versatility through Warcaster/Warlock choice. For example, Cygnar’s four in-faction themes are Heavy Metal (Warjacks), Storm Division (Lightning-centric), Sons of the Tempest (Gun Mages) and Gravediggers (Trenchers). Circle Orboros’ themes are Devourer’s Host (Tharn), Bones of Orboros (Wolds), Wild Hunt (Wolf Sworn) and Secret Masters (Druids). These allow players both new and old to make purchases, build their collections, and create lists using models that will thematically work together, helping combat some of the potential analysis paralysis, and you can easily just choose a concept that you really like and build an entire army around it, with the theme benefits actively rewarding you for your choices.
Basically, it’s a winning concept, so it’s no surprise that other companies have their own incarnations.