Not quite.
For clarification, you can add 9, 10 or hundreds of dimensions to any transaction if you want to.
However, you can only have 8 shortcut dimensions in total.
What this actually means is that you can only see 8 displayed on a line directly e.g. the sale line. To see the extra dimensions, you need to open a list of dimensions on the line or header.
If people are manually entering dimensions, their being on the line does make it much easier. Although manually adding 8 dimensions does pose efficiency and data accuracy challenges.
If the dimensions are being inherited from customers, vendors, items etc. the fact you can’t see them directly on the line isn’t really a significant issue.
If you do have 9 dimensions you wish to analyse by, you will be more empowered reporting through power Bi or jet than directly in BC.