While a scrum team should only consist of three components, there must be someone on the team that does the analysis work. It is good to have someone who understands the domain that the other team members can go to if they have questions. In allowing the team to have that initial meeting with the client, the team then takes the responsibilities of providing value to the client. That responsibility should not only rest on the scrum master or the product owner.
Also, all team members understand what is on the product backlog and although it is the job of the product owner to list the items on the product backlog, during sprint planning, the entire team decides on what to do for that sprint. This gives the technical people on the team the opportunity to also provide input on whether an item is more technically feasible to do now or later.
The idea is to allow the whole team to take on the responsibility of getting the work done. Five business analysts are always better than one, if all the team members are trying to understand the requirements, it is better than just one “business analyst”.
In the scrum rules, the product owner is the custodian of the product backlog; however, he/she does not decide on the order of the items in the backlog, he rather specifies the value each of the items gives to the client. The team should decide on the order in which items will be worked on in order to maximize the value to the client. It is important that there is transparency in the product backlog.
If for some reason the client wants to add new features, it is important that the product owner then notifies and explains these new items to the understanding of the team members. The advantage of this is that all team members have a clear idea of the things on the product backlog and hence during planning, it is easy for team members to decide what to work on.