Heavy ab work creates strong abs, not a strong core. You need to develop the core strength by handling heavy weight unassisted as well.
You should understand this 0ni. To get stronger you make the work harder. Once you are strong then you bring in the belt and lift more weight.
Correct me if I am wrong but I was under the impression that planks worked the entire midsection. Especially if you add weight and do them in the RKC form.
To get stronger you need to make the work harder.... I agree with this but I think you have to distinguish between a few methods of making work harder. Front squats and box pulls make squats and deadlifts "harder", so they are good as assistance for the squat and the deadlift. Wearing a belt does not put you at any sort of leverage advantage. I looked for ages to try and find some sort of conclusive information on this and I found that the evidence was here, there and everywhere. Some showing increase in emg activity, others not. I couldn't find anything that used at least a heavy squat or deadlift so the best I could find was isometrics and sustained endurance work. I finally came across the following quote:
"Teaching your clients' proper form and prescribing the appropriate exercises and loads appears to be the best primary intervention to reduce the risk of injury during exercise. However, a lumbar belt may provide a beneficial effect when performing maximal lifts, such as in power lifting. Finally, it is important for the trainer to realize that there is a complex interaction of the muscles, such as the abdominals (especially the obliques and transverse abdominals) and other sensory influences (such as proprioception and kinesthetic awareness) when doing lifting tasks that should always be considered when designing safe and effective exercise programs."
Now going back to my first point, which probably people missed as it wasn't completely outrageous (and my further points often link back to these which is probably why people miss them) is that I thought the best should come into play when the lifter starts to grind out lifts. This is going to be about a 9RPE right? The novice has no reason to travel up to this sort of RPE and for most novices under good training the first time they do this will be testing out their openers before a meet, or maybe not for an incredibly long time if they do not wish to compete (struggling to think of a real reason to demonstrate their strength). So this will most likely be when they start to wear the belt. Prior to this, there is no need as you do not need extra abdominal pressure to complete an 8RPE set. You just don't need it (remember we are talking about a novice here - Ricky Goodyear doing doubles with 300kg as an 8RPE is very different to Joe Bloggs doing 5x5x100kg)
So as I see it, looking at the evidence of how a belt works, the worst that can happen is that the belt offers lateral support. It doesn't really stop you from rounding your back, or twisting your spine but it does offer side to side support. I think that heavy midsection work should be a big part of every successful training regime, especially exercises that work the obliques such as planks, ab wheel rollouts, high rep pull-ups, farmers walks and so on. Most strong people will already do these and beginners should probably do these anyway simply because getting good at a shitload of exercises will make you better in the long run and the present is as good a time to start as any.
That only leaves one other aspect - Psychological. As I said I like to keep it so squatting naked feels normal and that I feel secure with the belt on. I do not like this the other way around where I feel normal with a belt and insecure naked. I don't want this to turn into two trains of thoughts jack each other off discussing who is right and wrong so I'll probably leave this at that.
Whether you wear a belt or not is entirely, 100%, personal choice and choosing to wear one or not has pretty much 0 impact on your training unless you plan on competing, in which you want to get every kg possible. Unless of course you're a sly fucker and get enjoyment from winning best lifter with no supportive gear and embarrassing other lifters for even showing up!