Explanation
The side effect of granting opportunity access to sales reps on the same team using ownership-based sharing rules is that all sales reps will have Read access to all accounts. This is because ownership-based sharing rules are based on the role or territory of the owner of the record, and they grant access to both the record and its parent account. Therefore, if a sharing rule grants Read access to opportunities owned by users in a certain role or below, it also grants Read access to the accounts of those opportunities4. Sales reps on the same team will not have Edit access to the accounts for opportunities owned by their peers, as sharing rules only grant Read or Read/Write access, not Edit access. Sales reps on the same team will not have Read access to the accounts for opportunities owned by their peers only, as sharing rules grant access to all accounts in the specified role or below, not just their peers. All sales reps will not have Read access to accounts for all opportunities, as sharing rules only grant access to accounts for opportunities owned by users in a certain role or below, not all opportunities.