It comes back to the point about accountability. Members of Parliament who behave in such a way would be taken to task, first by their Whips, secondly by the local party members, and finally by the electorate.
Since the end of the second world war, 65 countries have gained their independence from the United Kingdom. Although many have based the design and practices of their legislatures on might be called a Westminster model, I am not sure whether any of them have chosen to replicate a wholly unelected, appointed, partially hereditary Chamber where members serve for life. Even in Lesotho, with its hereditary chieftains, appointed members of the Senate serve a five-year term. Its Senate has 33 members, not over 800.
SNP manifestos in 2015, 2017 and 2019 called for the abolition of the House of Lords. When Scotland becomes the 66th country to achieve independence from the United Kingdom, there will be an opportunity to consider how the enactment of legislation, scrutiny of the Executive and representation of the population can be most effectively —and perhaps innovatively—achieved.
There have been proposals for an upper Chamber of some kind, perhaps based on the model of the Irish Seanad. There have been calls for an increase in the number of MSPs, both under current devolution and indeed under independence. There are more radical ideas for pre-legislative scrutiny and a greater use of citizens’ assemblies and other forms of direct democracy that could feed into the main legislature.
However, nobody, as far as I am aware, has suggested that when Scotland becomes independent, or when any other country has a good hard look at its constitution, it would be a good idea to have a wholly appointed second Chamber. The idea is just incomprehensible and incompatible with a modern democracy.