Shouldn't ONLY the sfp1 port in your diagram be purple in color? Apart from the WAN port that is yellow, shouldn't the remaining ports have no color?
Based on the legend, the purple port stands for a trunk port on the router; so it doesn't seem to make sense to have so many trunk ports on the router.

It is rather normal for a router to mostly have trunk ports.
Can be one, can be many.

Keep in mind that there is also a switch that connects via sfp1/2 to the router, please refer to the origin above. If the connection is via fiber from a switch, then it only makes sense to connect the other end to the fiber port on the router, and not on an ethernet port although one could do that (and pcunite does state connecting to ether ports as well) but then it defeats the purpose of connections via fiber. Why drive on 1st gear when you can switch to 5th gear?

I don't deny that there can be more than one trunk port, but if this article is meant for newbies and amateurs, it is unnecessarily confusing. For this reason alone, the other purple colored boxes should be uncoloured, and changes made accordingly to the router.rsc file.
The purpose of this entire post is to help newbies understand and how to perform various real-world configurations, that is the basic premise.

If one looks at the router.rsc file, it does say that the tagged ports can also be ether2-7, and therefore coloring them purple is in-line with the way the diagram is colored. I don't deny that. All I am saying is make it simple...plug a fiber port to a fiber port. Avoid saying it's OK to plug to a fiber port at one end and to an ethernet copper port at the other, in which case one is teaching the wrong thing to newbies.
pcunite also says the post is also meant for network admins, I am sure this fiber to copper connection would look silly to them.
More importantly, keep in mind that lots of us MT newcomers will be referring to the post as well, some would also be new to networking.

You are a forum guru, so it is easy for you. But the MikroTik journey for beginners is very very frustrating, I can attest to that, so why add more confusion? Remember the KISS principle?
If the intent of this posting is to help newbies, then the purpose is defeated by this unnecessary coloring, this is my opinion.

In any case, thank you for having taken the effort and time to reply.

I understand what you're aiming for but it's not that uncommon.
I have a router with a CSS610 switch connected via SFP+ at home and still most of my router ports are trunk ports (only 1 access port, the 2.5Gb one for direct connection to my PC in my office and ofcourse the ISP uplink).

I am not the author of the original posts but the way I see it his aim was mostly to provide clarity on how to use VLANs in a ROS environment.
This is not about why use VLAN, when to use trunk ports, when to use access ports, ...
Anyone able to grasp those VLAN related concepts, should be (I hope) smart enough to figure out when to use access ports and when to use trunk ports. This guide then gives you the handles how to implement it using ROS.

As far as being a guru, I'm far from. Don't let post count mislead you.
Still learning new things ... but I have been an absolute beginner too. I also started from zero with ROS and yes, the learning curve is steep.
But put in the time, experiment, start over and learn doing so.
Again, I do understand your position but I believe you're misunderstanding (a bit) the real aim of this thread.

Concur Holvoe........
The post made is nonsensical, based on the experience on this forum I have seen all manner of setups and none of the threads examples seem out of place compared to that of which one is exposed to here. The intent of the article is to help users navigate through implementing vlans via vlan-filtering=yes, and the examples are 'fictionary and any resemblance to actual configs is not intentional, nor were any bunny rabbits harmed during the process. The post misses the mark by a continental mile.