I'm somewhat at a loss to explain our feeling on this one too, because it really is just intuitive for native speakers. But for advanced non-native learners, I wonder if it might help just to consider the concept of extended time with each verb individually. The question to ask yourself might be 'Is it possible to continue doing this verb for more than a brief moment in time, for a somewhat extended period?'
'Attend (a conference),' then, is easy, because of course when the conference takes several hours or days, then attending it is an ongoing, continued action, something you will be doing for a while, not just in a brief moment.
You could contrast that with 'arrive at' and say something like 'I will arrive at the conference at 3:00.' But in fact, that sounds unusually formal, since we would usually say 'I'm going to' to express a plan or schedule. ('I will' expresses more a firm intention, a more seriously determined resolve.) And since travel isn't entirely predictable, we would also usually think of arriving as a somewhat longer activity, one that takes place within a relative time frame. So it would be entirely natural to say something like 'I'll be arriving at the hotel sometime mid to late afternoon / around 4 or 5:00.'
'Make' is a verb that probably is more often ongoing than not, because making anything usually takes some time. Similarly, 'compare' in the sense of 'make a comparison,' at least in a paper or presentation, usually takes several sentences or paragraphs to accomplish, if the comparison isn't trivial or obvious. So it also seems perfectly reasonable to say 'I will be comparing / making a comparison' when describing how you intend to construct an argument or a discussion of an issue, which is built up step by step, not made in a single sentence or statement.
However, you can certainly think of verbs that don't lend themselves as readily to the continuous. There are activities that are conceptualized as a single thing even though in practice they take a little time to complete, perhaps because they don't require extended thought? So you could theoretically say, for instance, 'I will be taking a shower / brushing my teeth,' but we normally wouldn't; we would just say 'I'm going to take a shower / brush my teeth.'
On the other hand, it's much less conceivable to say something like 'I will *be jumping off a bridge tomorrow,' because the verb itself intrinsically describes an action that takes only a moment, that doesn't have any significant duration.
Not sure if that helps, but it's the only way I can think of to approach the question.