There is no excuse to scream or seriously inconvenience others. The guides are not nurses or maids, they are guides. I have on occasion been with people who are not fit for the excursion perhaps it was the description or it may have been an error in judgement. In no case did they impose upon others except to politely ask where they could wait. A polite request usually gains the sympathy of all and if possible we will all slow down or take turns assisting.
as I often say, in travel you must be willing and able to alter your plans . If that means leaving the tour and taking a taxi back to the ship, do so. If the description was not adequate you can then take it up with HAL and request a refund. Nothing like requiring a refund to get them to write better descriptions.
i did notice on my last cruise that there were some more details in the descriptions but I agree with others there could be much more detail.