I commonly observe it that having no responsibility for implementation leads to impossible plans.
In meetings when plans are being discussed, often those without the responsibility for their implementation will argue for much tougher targets and objectives (to the point of fantasy) than those that have to do it. Often in relationships one partner will suggest a plan for the other to achieve, which on the face of it is not possible or will involve far more work and time than is available to devote to the task.
Moreover, the converse applies: those who have the responsibility for implementation are likely to be much more conservative about what is achievable.
Both views are corrupted by the responsibility, or not, for implementation. However, this tendency can be very useful if handled well.
The non-implementer can bring more creative suggestions forward without being shackled by implementation responsibility. Whereas the implementer can bring a heightened sense of realism of what is achievable to the discussions. The secret to success is to merge these two viewpoints and create achievable but stretching targets and plans.
If you are present at a meeting and detect this happening, then you should (especially if you are the chairman of the meeting) seek to bring about a discussion of the merits of each position and drive consensus with the non-implementer(s) being more realistic to the problems of implementation and the implementer(s) raising their appreciation of the opportunities of the situation.
The moral is that team work with participants of differing outlooks and responsibilities can raise the performance both in setting goals and achieving them.