I know some people and their carers deliberately avoid diagnosis and I can understand this.
However, there are some arguments for seeking a diagnosis:
1) There are drugs available which might help (they may not though and may have side-effects). And some forms of dementia do not really respond to any medication.
2) A diagnosis ought to give you access to a lot of valuable support. But people often report that this desirable result is not forthcoming.
3) Blood tests might show that dementia-like symptoms may be caused by a number of conditions which can often be cured or kept at bay: