Your argument suggests that a source is only valid if everyone can easily verify it.If such a criteria were used then you would not trust most academic books if the citations weren't of works and records easily and freely accesible to you.
Wikitree would also contain even more unsourced profiles and leafless branches than it already does.
There is no free site where you can see an image of any British census. Family search has incomplete transcripts of them. Similarly it has comparatively few sets of images online of parish registers, I don't think it has any from Scotland. The indexes are a poor substitute ; information gaps as usually only names are included (they are after all only an index), inevitable errors of transcription, sometimes whole parishes missing, sometimes with the earlier indexes burials were not listed.
It has to give just a few examples: no British wills, no criminal records, no poor law or apprenticeship documents . It has a valuable library of secondary sources but cannot, for copyright reasons, supply recent editions of books and journals.
I couldn't research the areas I research without paying for a subscription. I have access to Findmypast and some newspaper archives if I sign in via my University .Nevertheless, I pay for an Ancestry subscription simply because it has more of the sets of records that I regularly use . If I were researching Scottish ancestry then I would need to pay for access to Scotland's people.
On a personal level, I've transcribed very many wills (PCC wills, Wiltshire wills and Dorset wills) and placed the transcripts here on wikitree. If you don't have an ancestry subscription or the willingness to pay for a copy of each individual will from the archive, you won't be able check them. (I have to say, some of the recent condemnation of the use of 'ancestry sources has made me consider finding another platform for them)
There are also vast numbers of records in National and local archives all over the world. Most will never be digitised . I spent a long day recently working on one 16th century document at the National archives, I haven't finished and will have to return (requires a 3 hour each way journey ) At other times, I've researched at my local archives, closer. Should I refrain from adding my findings to wikitree because others can't check it from the convenience of their armchair at home?
I think wikitree should be celebrating the fact that it has members who do subscribe to commercial sites and are willing to share their findings. It should also be actively harnessing the ability of its members to visit local archives in many parts of the world. Or do we just want a copycat version of the family search tree?
