Common amount to offer on property [Scotland]

I saw on this forum while perusing that if some property is "offers over X", then just offer X ("why offer more than asking?" is roughly what I was seeing). However, solicitor insists that you need to offer 10 - 20% above the valuation in the home report otherwise you're pretty much going to be rejected. So for example, some property is "offers over £190000", valuation in home report is, say, £200000, so you need to offer somewhere between £220000 and £240000 to have a chance. This seems a bit crazy to me that we have to pay so much more than what it's actually worth according to a professional surveyor. In addition, if this is just "how it is", then why do they not just say explicitly they won't accept anything less than at least £(1.1 * valuation)? The whole thing just seems so ridiculous to me.