While almost all Windows 10 PCs can download the Creators Update, that doesn’t seem to be the case for Windows 10 Mobile. Just like what has happened before when Microsoft dropped a lot of Windows Phone 7 from the switch to Windows Phone 8 and even from Windows Phone 8 to 10. A handful of Windows 10 Mobile devices will also only be getting the Creators Update. These include Lumia 550 and above, Alcatel Idol 4S, HP Elite X3, and VAIO Phone Biz, among a few others.  

The reason is Microsoft wants to set performance expectations for the update. According to Microsoft’s Dona Sarka, there have been complaints about Windows not offering the “best possible experience” on older devices, which means your older device might not be able to handle the Creators Update and not offer you the experience you expect it can provide for you. 

Source: Engadget