As mentioned above, there is a huge amount of misinformation about IFR in the FS community. A lot of that can be traced to the manner in which people learn.
Most simmers first exposure to IFR is either in an aircraft like the TBM, or more likely, an A320/737/747. Therefore people inevitably learn what they need to in order to operate their chosen aircraft. After some time, they can even be come relatively proficient at operating these aircraft, with a sound understanding of the FMC, autopilot modes, etc.
So many people end up completely skipping the traditional, liner learning path, and jumping straight into the advanced, high level airline type operation. Their IFR knowledge is therefore correspondingly fragmented. As they say, a little knowledge is dangerous, and so many people with ‘some’ knowledge and understanding of IFR, believe their assumption regarding topics and procedures that they simply haven’t explored or experienced in detail. It can therefore be very difficult to decipher the right from the wrong in flight sim related communities such as here.
This is not a criticism or casting judgment, flight simulation is ultimately an entertainment product, and people are free to enjoy it however they desire.
If I can offer any advice to those really interested in learning the ins and outs of IFR flight, it’s to take it slow, and try to stick to a semi realistic learning pathway. Start in a 172 or similar, and lean enroute radio aid navigation until you are completely comfortable. Then look at GPS navigation. Once your understanding grows, continue on to instrument approach procedures, again starting with NDB and VOR approaches, before tackling ILS and RNAVs. Again, when comfortable, progress onto faster more advanced aircraft like the TBM or King Air.
Also, if possible, try and combine time in glass cockpit aircraft with analogue gauge aircraft. Whilst glass cockpits are tremendous, the amount of information and feedback they provide can sometime mask your understanding of the underlying concepts. Analogue gauges are harder to master, but I feel you can learn so much more from them.
Once you are completely at ease with the above, you can add the most misrepresented aspect of IFR flight, communication. Personally, I’d say half the challenge of IFR is understanding and correctly communicating with ATC, other aircraft etc. Something like VATSIM is a great resource, but if you really want to increase you understanding, Pilots Edge is unbeatable. They have an incredible set of tutorials that start from basic point to point flights, all the way up to flights with complex routing, multiple approaches and diversions. You do however need a solid foundation of navigation and approach knowledge/skill before making this jump.
6 months following a pathway such as this will teach you infinitely more about IFR flight, than flying around in an A320 or 787 for the same time frame. All you’ll really get good at there is using the FMC and autopilot.