That is my understanding too. I believe we saying an external SSD will compensate? I am only a hobbyist so am not prepared to pay a small fortune for a high end iMac?
The good news is, none of this would be a reason for you to buy a high-end Mac. What I talk about below applies to any Mac or PC.
The nice thing about most new Macs is that the internal storage is already high end. What I mean by that is the speed. Most use the fastest type of SSD (NVMe at over 2000MB/sec).
When Cletus talks about the basic SSD in low-end Macs being inadequate, he’s talking about the capacity — the storage capacity in base models is usually too small for intensive graphics work. And that is correct. But all you have to do is add more, not buy a different Mac.
The important thing to understand is what the additional storage is for. Internal storage has to be large enough for all the applications you want to install, and all of the documents you want to store long term on the Mac itself…
plus an extra 100-200GB (some say 10-20%) for large temporary files that are regularly created by the operating system and major creative applications. For example, the Previews file and the Camera Raw cache managed by Lightroom Classic and Adobe Camera Raw, and the Scratch Disk virtual memory files managed by Photoshop.
As an example, if you think macOS + your applications will need 100GB, and your documents will need another 120GB (let’s assume you want to keep the bulk of your photos/videos on external storage), that’s 240GB. On a Mac with 256GB storage, that would leave only 16GB free…a dangerously low amount of free space in my book, so that would mean the Mac should be ordered with at least 512GB of internal storage. The big reason to watch free space on an SSD is that a full SSD can slow to a crawl…and when you paid more for a very fast type of SSD as you have in Macs, that slowdown is something you want to avoid causing.
What I want to point out there is that you have to be aware of what can go on external storage (usually documents including photos), and what must go on internal storage (applications and most types of temp files) to understand where you need to buy more. Because you can’t add more internal storage after purchase to most new Macs, it’s especially important to carefully work out how much internal storage you will need during the life of that Mac.
It can also be important to understand which temporary files can be relocated to external storage. For example, you can keep your Lightroom Classic folder (which includes the potentially large Previews file) on an external drive, and you can have Photoshop assign its scratch files to a different external drive. This strategy of sending both large temp files and large source files to multiple fast external drives is also common in the video/audio editing world, because it means the internal storage can be smaller and doesn’t have to work so hard.