Block visitor from changing text in Form block placeholder

Please add the possibility to block a visitor from changing the preset text in the form block placeholder (or standard value). For example if someone buys something, in most countries the seller (company, school) has an obligation to be able to proof afterwords they presented enough information in the form itself. Right now the buyer/student can change all preset text in all the text fields… so the whole concept of proof is gone. In the form builders that I know, I can simply check 'text may not be edited by visitor' or similar. Right now we use (your) CSS to block this. .no-edit-field { pointer-events: none; }