I think it does matter, because the number of members of the EC is set at the AGM. So if someone steps down/resigns, the number stays the same but you are one member short. So if you need to have a quorum, the number of members you need is determined by the number of members set at the AGM, e.g. 5 members, three for a quorum. This can create problems, e.g. if you have a meeting and only two people turn up.
I have raised the issue before re how an EC member is appointed if someone drops out, I think the legislation is defective, as it doesn’t make sense to have to call a general meeting to appoint someone to a casual vacancy, which is what the legislation suggests.