No you do not have to assume everybody has a Suite.
This is the Premiere forum and i think the first answer should be to find a way to get things done with Premiere.
If there is absolute no way to solve it with Premiere then other software could come in.
There is a awfull lot you can do with Premiere, where you do not need After Effects or Photoshop.
However If you do have a Suite those programs can make it a lot easier.
But do not assume everybody has a Suite because they dont.
I do usually assume the user has the suite unless they specifically state that they do not. I think that other people do assume this as well. Photoshop is very common and so it wouldn't be unusual for someone to have Photoshop anyway, regardless of the suite.
I'm not saying that it is correct to make this assumption, just that you are correct in observing that this assumption is becoming the norm.
Of course, PPro does come with Encore and Adobe Media Encoder so references involving those programs wouldn't be assuming anything else. I think part of the reason this is becoming the norm is because it's almost a no-brainer in terms of price for many video producers. It's like a buy one get one free type deal at the grocery store...you don't "have" to buy the 2nd one, but most people will because of the total savings.
If there's a tedious way of doing something in Premiere Pro and an easier way in After Effects, I tell people about the easier way in After Effects... often after Ann or someone else has explained the tedious way in Premiere Pro. Text animation is the most obvious example, but it's also true with a lot of compositng features.